Particle-measuring system and particle-measuring method

ABSTRACT

The present invention provides a particle measuring system which is provided in a processing system  40  which generates an atmosphere obtained by exhausting air or a gas in a processing chamber  48  by a vacuum pump  98  and applies a process concerning semiconductor manufacture to a wafer W in the atmosphere, attached to an exhaust pipe  90  which connects an exhaust opening  86  of the processing chamber  48  with the vacuum pump  98 , and measures the number of the particles in the exhaust gas, and a measuring method thereof, the system and method providing a processing system and a cleaning method which terminate etching process by determining an end point based on the number of the particles in the exhaust gas and perform cleaning of unnecessary films.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Divisional application claims the benefit of priority under35 U.S.C. §120 to application Ser. No. 10/321,646, filed on Dec. 18,2002, which is Continuation-in-Part of application Ser. No. 09/594,479,filed Jun. 14, 2000, now U.S. Pat. No. 6,532,069, and under 35 U.S.C.§119 from Japanese Applications No. 11-168968, filed Jun. 15, 1999 and2001-392703 filed Dec. 25, 2001, the entire contents of each of whichare incorporated herein by reference.

DESCRIPTION OF THE RELATED ART

The present invention relates to a particle-measuring system that ismounted on a processing unit for forming a film on a semiconductor waferby using a gas, and that measures the number of particles included in anexhaust gas discharged from the processing unit.

Generally, in the manufacturing of semiconductor integrated circuits,various kinds of processing units are used for processing semiconductorwafers (hereinafter to be referred to as wafers) as objects to beprocessed at various manufacturing stages, including a film deposition(CVD: chemical vapor deposition) process, thermal oxidation and impuritydiffusion processes, an etching process, a film forming (sputtering)process, a thermal processing process, etc.

In the film forming process, thin films such as a silicon oxide (SiO₂)film, a silicon nitride (SiN) film, and the like are deposited asinsulation layers or insulation films on the surface of the wafer using,for example, a CVD unit. For forming wiring patterns and embeddingtrenches, thin films of tungsten (W), tungsten silicide (WSi), titanium(Ti), titanium nitride (TiN), titanium silicide (TiSi), etc. aredeposited.

When these processing systems are used to carry out each processing, itis necessary to avoid as far as possible the generation of particlesthat become the cause of reduction in product yield.

Therefore, a particle-measuring system is installed on the processingsystem in order to real-time monitor the state of generation ofparticles within a processing chamber or in order to know the timing forcleaning the processing chamber. Particularly, in the film-formingsystem such as a CVD system or a sputtering system, there occurs anadhesion of unnecessary films onto the inner wall of the processingchamber or onto the surface of the parts. These unnecessary films aredisposed and accumulated within the chamber during the film-formingprocess. These unnecessary films are easily peeled off at the nextfilm-forming cycle, and particles are easily generated. Therefore, ithas been important to monitor the volume of particles generated duringthe film-forming process.

One example of a processing system having a conventionalparticle-measuring system will be explained with reference to FIG. 18.

A mounting table 4 for mounting a wafer W is provided inside aprocessing chamber 2 of almost a cylindrical shape, and a transmissionwindow 6 made of quartz glass is disposed on the bottom of the chamber.A plurality of heating lamps 10 are disposed on a rotary table 8 belowthe transmission window 6. Heating beams irradiated from these heatinglamps 10 are transmitted through the transmission window 6 to heat thewafer W on the mounting table 4.

A shower head 12 for introducing a processing gas such as a film-forminggas into the processing chamber 2 is provided on a chamber ceiling thatfaces the mounting table 4. Four exhaust openings 14 (only two openingsare shown in the drawing) disposed with approximately equal intervalsare provided on the periphery of the bottom of the processing chamber 2.Each of these exhaust openings 14 is connected to an exhaust pipe 16extending downward.

Respective discharge sides of the exhaust pipes 16 are assembled intoone, which is then connected to one absorption side of an assemblingpipe 20 of a large diameter. A butterfly valve 18 for adjusting pressureis provided inside the assembling pipe 20. A vacuum pump 22 is providedat a discharge side of the assembling pipe 20, and a main exhaust pipe24 of a relatively large diameter is connected to a discharge side ofthe vacuum pump 22. Atmospheric air and a gas within the processingchamber 2 are exhausted to the outside by this vacuum pump 22. Aparticle-measuring system 26 for counting the number of particlesincluded in the exhaust gas is provided in the middle of the mainexhaust pipe 24.

FIG. 19 is a diagram showing a cross-sectional configuration of the mainexhaust pipe 24 provided with the particle-measuring system 26.

The particle-measuring system 26 has a laser beam irradiator 28 foremitting laser beams L and a stopper 32 for suctioning the emitted laserbeams L disposed opposite to each other so that a line connectingbetween the two units pass through a center O of the main exhaust pipe24. Further, a scattered light detector 30 for detecting scatteredlights SL generated by a collision of the laser beams L againstparticles P in the middle of the irradiation of the laser beams L, isdisposed facing the center O of the main exhaust pipe 24.

Based on this arrangement, for measuring the particles, the scatteredlight detector 30 detects the scattered lights SL that are generatedwhen the laser beams L irradiated from the laser beam irradiator 28 havecollided against the particles P that move within the main exhaust pipe24. The particle-measuring system 26 counts the number of the particlesincluded in the exhaust gas based on this detection.

According to the above-described conventional processing unit, theparticle-measuring system 26 is provided on the main exhaust pipe 24 atthe discharge side of the vacuum pump 22 that assembles the exhaustpipes 16 from the processing chamber 2 together. Of course,abnormalities of products adhere onto the inner walls of the exhaustpipes and blades of the pump and the valve due to the exhaust thatoccurs during the process from the processing chamber 2 to theparticle-measuring system 26. These adhered abnormalities are peeled offirregularly, and these generate new particles.

As the particles generated irregularly are added to the dischargedparticles that have actually been generated from within the processingchamber 2, it has not been possible to accurately grasp the number ofparticles that have been generated from within the processing chamber 2.

Further, the exhaust gas is swirled within the exhaust pipe near thedischarge side of the vacuum pump 22. Therefore, the same particlescross the laser beams repeatedly, and they are counted by a plurality oftimes.

In principle, the actual number of particles within the processingchamber 2 should be highly correlated with the count number based on themeasurement of particle by the particle-measuring system 26. However,for the above reason, there is a very low correlation between the twodata. Therefore, according to the conventional particle-measuringsystem, it has been difficult to accurately understand the state ofparticles actually generated from within the processing chamber 2.

Further, for example, when forming a thin film by a film-forming system,e.g., a CVD system, generation of particles which can be a factor ofreduction in a yield of a product must be suppressed as low as possible.These particles are generally produced when an unnecessary film that hasadhered to a surface of an internal structure, such as an inner wallsurface of a process chamber, a mounting table or a shower headstructure, flakes away. Therefore, after subjecting one lot (forexample, 25) of wafers to film formation processing periodically ornon-periodically, there is carried out etching processing which removesan unnecessary film by introducing a cleaning gas, such as ClF₃, intothe processing chamber, namely, cleaning processing. Generation of theparticles in the processing chamber can be suppressed by this cleaningprocessing.

Since the cleaning gas is highly active, the inner wall surface of thechamber and other internal structures are also scraped away after theunnecessary film is removed, if cleaning processing is carried outlonger than necessary. Therefore, it is very important to monitor thescraping state of the wafer during the processing, and determine anappropriate end point (point at which the etched film is removed), inorder to terminate the cleaning processing with a just timing.

Description will now be given as to a conventional method fordetermining termination of the cleaning processing, i.e., the end point.

For example, there is a set a sequence to perform the cleaningprocessing for a predetermined time every time a predetermined numberof, e.g., one lot (25) of wafers to be processed is subjected to filmformation processing. At this moment, the predetermined number of wafersare actually subjected to the film formation processing, and anunnecessary film is deposited on the inner wall surface of the chamberor the internal structure. A cleaning processing time to remove theunnecessary film or an interval of execution of cleaning isexperimentally obtained, and the cleaning processing is carried outbased on such a time or interval. At this moment, the cleaningprocessing time may be determined by utilizing a plasma monitor. Whenthe unnecessary film is, e.g., a silicon oxide film and the internalstructure is, e.g., stainless, the color (wavelength) of light generateddiffers depending on the plasma. Therefore, the color of the plasmavaries at a switching part in accordance with etching. The point in timeat which the etched film (unnecessary film) has been completely removed,thus exposing a substrate (internal structure and the like) underneath,is referred to as “just etch”.

In actual cleaning processing, the cleaning processing is not terminatedat just etch, and is continued for a predetermined period. In order tocompletely remove an unnecessary film which has adhered to a part whereremoval of the unnecessary film is difficult, as compared with amounting table surface where removal of an unnecessary film is easiest,over etching, in which etching processing is prolonged for apredetermined period after the just etch point is carried out, and thenthe cleaning processing is terminated.

The over etching period is approximately ½ the time required from startof the cleaning processing to the just etch point. Therefore, if 300seconds are required from start of the cleaning processing to the justetch point, cleaning processing continues for a further 150 seconds,thus cleaning processing reaches the end point after performing etchingfor a total of 450 seconds.

However, in the actual processing, there is rarely a case that one lot(for example, 25) of wafers to be processed is periodically supplied andmanufactured. Therefore, when one lot slightly exceeds 25, severalwafers are processed in the last processing. Furthermore, there may be acase that only a few wafers are subjected to film formation processing,and the film-forming system stays in the idling state for a long timeuntil the next wafer to be processed is supplied, and the adherentunnecessary film may possibly change its nature in the processingchamber. Therefore, the cleaning processing is necessarily executedbefore entering the idling state.

In such a case, the thickness of the adherent unnecessary film isslightly less than the predetermined film thickness. Thus, by executingthe regular cleaning processing mentioned above, the inner wall surfacein the chamber or the internal structure, e.g., the surface of themounting table, a shield ring, a shower head structure and others may bescraped away by excessive etching, or the surface of that member may bedamaged by etching or corrosion. There occurs a problem that theduration of life of the internal structure is shortened by this damage.When a frequency of replacement of the internal structure becomes high,an operating rate of the system is deteriorated, and the throughput islowered, which results in a problem that a product cost is adverselyaffected.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a particle-measuringsystem capable of grasping a state of generation of particles by keepinghigh correlation between the number of particles generated and exhaustedfrom within a processing chamber and the counted number of particlesbased on an accurate counting of the number of particles exhausted.

Moreover, it is another object of the present invention to provide aprocessing apparatus and a cleaning method which can automaticallyassuredly grasp a timing of the just etch, determine an end point,appropriately terminate the etching processing and perform cleaning ofan unnecessary film deposited in a processing chamber irrespective ofthe number of objects to be processed before starting the cleaningprocessing.

The present invention provides a particle-measuring system mounted on aprocessing system that has a processing unit for carrying out apredetermined processing of an object to be processed and an exhaustsystem for exhausting an atmospheric gas from within a processingchamber of the processing unit by a vacuum pump. Within the processingsystem, the particle-measuring system is installed on an exhaust pipethat forms a part of the exhaust system communicating between an exhaustopening of the processing chamber and the vacuum pump. With thisarrangement, the particle-measuring system measurers the number ofparticles included in the exhaust gas discharged from within theprocessing chamber.

The particle-measuring system is constructed of a laser beam irradiatorfor irradiating laser beams to within the exhaust pipe so that the laserbeams pass along a line connecting between a center point of a crosssection of the exhaust pipe and a center axis passing vertically throughthe center of the processing chamber, and a scattered light detectorprovided in a direction approximately orthogonal with an irradiationdirection of the laser beams, for detecting light scattered fromparticles.

The present invention also provides a particle-measuring method formeasuring the number of particles included in an exhaust gas exhaustedfrom a processing device for generating an atmosphere includingatmospheric air or a gas exhausted from within a processing chamber by avacuum pump, and for processing an object relating to a semiconductormanufacturing in this atmosphere, the method comprising the steps of:modeling parameters; carrying out a numerical simulation for expressingtracks of an exhaust gas that includes particles flowing through anexhaust pipe; carrying out a track numerical simulation of an exhaustgas and particles; confirming an optimum position for measuringparticles; determining sensor installation position; installing thesensor; and evaluating a measurement of particle, wherein tracks ofparticles that flow through the exhaust pipe after the particles havebeen generated inside the processing chamber and exhausted from theprocessing chamber are simulated, to select an area where the density ofthe particles is the highest in the radial direction of the exhaustpipe, a laser beam irradiator is disposed at a position in this areawhere laser beams for measurement pass through, and a scattered-beamdetector is disposed in a direction orthogonal with the laser beams,thereby to measure the particles.

The present invention further provides a particle-measuring method formeasuring the number of particles included in an exhaust gas exhaustedfrom a processing device for generating an atmospheric air or a processgas exhausted from within a processing chamber by a vacuum exhaustsystem, and for processing an object relating to a semiconductormanufacturing in this atmosphere, the particle measuring method using adevice having a laser irradiator, a scattered-beam detector and a beamstopper for measuring the number of particles by irradiating laser beamsto particles generated within the processing chamber, theparticle-measuring method comprising the steps of: selecting an area inwhich the density of particles is high by carrying out a simulationbased on information on constructional members including the processingchamber and other members disposed inside the processing chamber,information on the vacuum exhaust system, and information on the processgas; adjusting a position of the laser beam irradiator so that the laserbeam. irradiator can irradiate laser beams in an area in which thedensity of particles is high based on the simulation; adjusting aposition of the beam stopper to face the laser irradiator so that thebeam stopper can receive laser beams passed through the high-densityarea; adjusting a position of the scattered-beam detector so that thescattered-beam detector can detect scattered beams of the laser beamspassed through the high-density area; irradiating by the laserirradiator the laser beams to an area in which the density of particlesis high; detecting by the scattered-beam detector the scattered beams ofthe laser beams passed through the high-density area; and calculatingthe number of particles from the scattered beams detected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram showing a processing system on which aparticle-measuring system relating to a first embodiment of the presentinvention is mounted;

FIG. 2 is a top plan view showing a positional relationship between atransmission window and exhaust openings within a processing chamber;

FIG. 3 is a diagram showing an installation state of theparticle-measuring system;

FIG. 4 is a flowchart for explaining a manufacturing of a processingsystem on which the particle-measuring system is to be mounted;

FIG. 5 is a flowchart for explaining a numerical value simulation forcalculating a position of installing the particle-measuring system onthe processing system;

FIG. 6 is a diagram showing a model inside the processing chamber and anexhaust pipe obtained based on the simulation;

FIG. 7 is a graph showing a correlation between the number of particleswithin the processing chamber and the number of particles measured bythe particle-measuring system;

FIGS. 8A, 8B and 8C are diagrams showing a first example of a particledistribution according to a simulation relating to the presentembodiment;

FIGS. 9A, 9B and 9C are diagrams showing a second example of a particledistribution according to a simulation relating to the presentembodiment;

FIG. 10 is a diagram showing a modification of an installation state ofthe particle-measuring system in the present embodiment;

FIG. 11 is a diagram showing another modification of an installationstate of the particle-measuring system in the present embodiment;

FIG. 12 is a graph showing an evaluation result of a measurement of thenumber of particles by passing laser beams through a portion (a point P)of a high particle density within the exhaust pipe in theparticle-measuring system according to the present embodiment shown inFIG. 10;

FIG. 13 is a configuration diagram showing a processing system on whicha particle-measuring system relating to a second embodiment of thepresent invention is mounted;

FIG. 14A and FIG. 14B are diagrams showing detailed constructions of theparticle-measuring system relating to the second embodiment of thepresent invention;

FIG. 15 is a diagram showing one example of a particle distributionstate obtained by a simulation according to the second embodiment;

FIG. 16 is a diagram showing a positional relationship among a laserbeam irradiator, a stopper member and a scattered light detector whenthe simulation data has been applied to the second embodiment;

FIG. 17 is a graph showing an evaluation result of a measurement of thenumber of particles by passing laser beams through an exhaust pipe in aconventional particle-measuring system shown in FIG. 19;

FIG. 18 is a configuration diagram showing one embodiment of aprocessing system on which the conventional particle-measuring system ismounted;

FIG. 19 is a diagram showing an installation state of the conventionalparticle-measuring system;

FIG. 20 is a view showing a structural example of a processing systemaccording to a third embodiment having a particle measuring portionmounted thereon;

FIG. 21 is a block diagram showing a cleaning end point determinationportion;

FIG. 22 is an explanatory view for illustrating a principle ofdetermining an end point of cleaning processing;

FIGS. 23A and 23B are views showing results of examining the correlationbetween a just etch point and increase/decrease in the number ofparticles;

FIG. 24 is a flowchart for illustrating a process of determining anetching end point in time;

FIG. 25 is a view showing a structural example of a processing systemhaving a push-up pin and its drive mechanism mounted thereon;

FIGS. 26A to 26D are process charts for illustrating a film-formingprocess;

FIG. 27 is a flowchart for illustrating a continuous film-forming methodof a titanium film/titanium nitride film as a first example;

FIG. 28 is a flowchart for illustrating the continuous film-formingmethod of a titanium film/titanium nitride film as a second example;

FIGS. 29A to 29D are views showing a degree (%) a chip number dependingon presence/absence of each gas or when a flow quantity of each gas ischanged;

FIGS. 30A and 30B are views for illustrating a structure of an objectdelivering mechanism in a mounting table adopted inn a third embodiment;

FIG. 31 is a view showing a cross-sectional structure of a firstmodification of the delivering mechanism;

FIG. 32 is a view showing a cross-sectional structure of a secondmodification of the delivering mechanism;

FIG. 33 is a view showing a cross-sectional structure of a thirdmodification of the delivering mechanism;

FIG. 34 is a view showing a cross-sectional structure of a fourthmodification of the delivering mechanism;

FIG. 35 is a view showing a cross-sectional structure of a fifthmodification of the delivering mechanism;

FIG. 36 is a view showing a structure of a gas mixing portion whichintroduces a process gas;

FIG. 37 is a cross-sectional view showing a structure inside a casing431 of a gas introducing portion; and

FIG. 38A is a view showing the relationship between an NH₃ gas ratiowith respect to all gases and a degree of the chip number, and FIG. 38Bis a view showing the relationship between an NH₃ gas ratio with respectto an H₂ gas and a degree of the chip number.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be explained in detail withreference to the drawings.

FIG. 1 is a configuration diagram showing a processing system on which aparticle-measuring system relating to a first embodiment of the presentinvention is mounted. The present embodiment will be explained by takinga CVD system as one example of a processing system for forming films ona semiconductor wafer (hereinafter to be referred to as a wafer) as anobject to be processed. It is of course possible to similarly apply theparticle-measuring system to other processing systems such as asputtering system and an etching system.

The CVD system 40 is broadly constructed of a processing unit 42 forforming a film by using a film-forming gas on a wafer W, and an exhaustunit 44 for discharging atmospheric air and a film-forming gas withinthe processing unit 42. A particle-measuring system 46 for measuring thenumber of particles included in the exhaust gas flowing through theexhaust unit 44 is mounted on the CVD system 40.

The particle-measuring system 46 is controlled by a controller/processor41 to carry out an arithmetic processing and the like. There is alsoprovided a display 43 for making a display of processing results andexpressions and various parameters to be used for simulations.

The control and process section 41 may be provided in or outside thesystem control section that controls the entire processing system.

This processing unit 42 has a processing chamber 48 made of aluminum(Al) in a cylindrical or boxed shape, for example. A cylindricalreflector 50 extending upward from the bottom of the processing chamber48 is disposed within the processing chamber 48. Further, a mountingtable 52 for mounting the wafer W thereon is installed on the reflector50. This reflector 50 is formed using aluminum as a heat-ray reflectivematerial, for example. The mounting table 52 is formed using a carbonmaterial having a thickness of about 1 mm or an aluminum alloy such asaluminum nitride (AlN).

A plurality of lifter pins 54, for example, three lifter pins (only twolifter pins are shown in the example) that move together in up and downdirections are disposed below the mounting table 52. A driving unit notshown drives the lifter pins 54 to lift the wafer W upward from thebottom surface of the mounting table 52 through lifter pin holes 58formed on the mounting table 52. The wafer W is lifted upward by theselifter pins 54, and is carried inside the processing chamber and to theoutside by a carrying mechanism having an arm or the like not shown.

A ring-shaped shield ring 60 for guaranteeing a uniform surface of afilm deposited on the wafer surface is provided at the periphery of themounting table 52.

Further, a transmission window 62 made of a heat-ray transmissionmaterial of quartz or the like is provided on the bottom of theprocessing chamber below the mounting table 52 to seal the chamberair-tightly. Further below this transmission window 62, there isprovided a boxed-shaped heating room 64 to encircle the transmissionwindow 62.

Within this heating room 64, a plurality of heating lamps 66 as a heatsource are installed on a rotary table 68 working also as a reflectionmirror. This rotary table 68 is connected to a motor by a rotary axis,and is rotated according to the rotation of the motor 70. It is possibleto uniformly heat the wafer W based on this rotation.

Heat beams emitted from the heating lamps 66 are transmitted through thetransmission window 62 to irradiate the bottom surface of the mountingtable 52 to heat the back side of the wafer W. As the heating source, itis also possible to use a resistance-heating heater by having theresistance-heating heater embedded on the mounting table 52, in place ofthe heating lamps 66. Alternatively, it is also possible to heat theback side of the wafer W by blowing a heating medium such as a heatedgas onto the mounting table 52.

On the ceiling of the processing chamber that faces the mounting table52, there is provided a shower head 72 having a large number of gasinjection holes 78 for introducing a processing gas such as afilm-forming gas into the processing chamber 48. This shower head 72 isformed in a round box shape using, for example, aluminum or the like,and is formed with a gas introduction opening 76 for supplying a gasbased on a connection to a gas introduction system not shown.

On the outer periphery of the mounting table 52, a ring-shapedrectification plate having a large number of rectification holes 80 issupported in up and down directions by a supporting column 84 formed ina ring shape. A plurality of exhaust holes 86 are formed on the bottomof the chamber below this rectification plate 82.

FIG. 2 is a top plan view cut along a line A-A of FIG. 1 showing apositional relationship between the transmission window and the exhaustholes within the processing chamber. As shown in FIG. 2, in the presentembodiment, four exhaust holes 86 are provided in approximately an equalinterval along the periphery of the bottom. An exhaust pipe 88 isprovided for each exhaust opening 86.

Each exhaust pipe 88 is connected in air tight to each exhaust pipe 90that forms a part of the exhaust system 44 via a gasket based on acoupling not shown.

These exhaust pipes 90 have straight tubular shapes at the risingportions, and their discharge sides are assembled into one, which isthen connected to an assembling pipe 94 having a relatively largediameter. A butterfly valve 96, for example, for adjusting the internalpressure of the processing chamber 48 is provided inside the assemblingpipe 94. A vacuum pump 98 such as a turbo molecular pump is provided ata discharge side of the assembling pipe 94. A main exhaust pipe 100 of arelatively large diameter is connected to a discharge side of the vacuumpump 98. Atmospheric air and a film-forming gas within the processingchamber are exhausted to the outside from the chamber through the mainexhaust pipe 100 by this vacuum pump 98.

A particle-measuring system 46 for counting the number of particles isprovided in the middle of one or more of the four exhaust pipes 90 ofthe CVD unit.

A film-forming processing by the CVD unit of the present embodiment willbe explained next.

At first, a gate valve G provided on the side wall of the processingchamber 48 is opened, and the wafer W is carried into the processingchamber 48 with a carrying arm not shown. The wafer W is delivered tothe lifted lifter pins 54. Then, the lifter pins 54 are lowered to mountthe wafer W on the mounting table 52. The carrying arm is then retiredand the gate valve G is closed. Thereafter, the atmospheric air withinthe processing chamber 48 is exhausted by the exhaust system 44.

As a processing gas from a processing gas source not shown, gases of WF₆(a raw material gas), SiH₂Cl₂, Ar, etc. are supplied by a predeterminedvolume for each gas to the shower head 72, and the gases are mixedtogether to form the processing gas. The processing gas is then suppliedapproximately uniformly to within the processing chamber 48 from the gasinjection holes 78.

The supplied film-forming gas is suctioned and exhausted from eachexhaust opening 86 to the exhaust system 44, and the inside of theprocessing chamber 48 is set to a predetermined vacuum level. Theheating lamps 66 are operated to emit light beams by rotating the rotarytable 68 to irradiate the heating beams onto the wafer W from the backside of the mounting table 52. Thus, the wafer W is promptly heated to apredetermined level of temperature, and this temperature is maintained.

A predetermined chemical reactance of the film-forming gas occurs in theatmosphere within this processing chamber 48. As a result, tungstensilicide, for example, is deposited on the surface of the wafer W.

The film-forming gas within the processing chamber 48 flows down as anexhaust gas through each exhaust pipe 90 from each exhaust opening 86.All the exhaust gases from the exhaust pipes 90 are collected inside theassembling pipe 94. The collected exhaust gas passes through the vacuumpump 98 while being pressure-adjusted by the pressure-adjusting valve96, and is discharged to the outside of the system from the main exhaustpipe 100. The particle-measuring system 46 counts the number ofparticles included in the exhaust gas.

The particle-measuring system 46 will be explained next.

As shown in FIG. 3, each particle-measuring system 46 consists of alaser beam irradiator 102 having a laser device for irradiating veryfine laser beams L, a stopper member 104 disposed opposite to the laserbeam irradiator 102 through a center axis 91 of the exhaust pipe 90, anda scattered light detector 106 of a light receiving element installed onthe pipe wall in a direction approximately orthogonal with theirradiation direction of the laser beams L. The laser element describedabove is a semiconductor laser element which is small in size and formedof GaAlAs, for example.

The laser beam irradiator 102 is provided on the pipe wall so that theirradiated laser beams L pass along a line connecting between a centeraxis 92 of the chamber and a center point O of the cross section of thecenter axis 91 (reference FIG. 1) of the exhaust pipe 90.

The laser beams L may be in irradiated in any direction so long as theirradiated laser beams L are directed to the direction in which thecenter axis 92 of the chamber exists through the center point O of thecross section. However, a relative positional relationship with thescattered light detector 106 is maintained.

The stopper member 104 suctions the laser beams L to avoid thegeneration of a diffuse reflection or the like of the laser beams Lwithin the exhaust pipe 90.

The scattered light detector 106 made of the light receiving element orthe like is provided on the pipe wall in a direction approximatelyorthogonal with the irradiation direction of the laser beams L as shownin FIG. 3. hen the laser beams L are irradiated onto particles P (108)included in the exhaust gas, the scattered light detector 106 receivesscattered lights SL that have been generated by the irradiation of thelaser beams L. As described later, the center of the scattered lightdetector 106 is not directed toward the center point O of the crosssection, but is disposed in an offset distance H3 that has been offsetas shown in FIG. 3.

A position H2 for installing the particle-measuring system 46 on theexhaust pipe 90 is determined based on a computer simulation to becarried out according to a flowchart as shown in FIG. 4. One example ofthis computer simulation will be explained next.

First, an outline of the processing system is scheduled. Specifically, abasic system design (process conditions) including a chamber capacity,an exhaust ability, a kind of a film-forming gas, a gas supply system, alength and a diameter of an exhaust pipe, etc., is determined. Next, theinstallation distance H2 of the particle-measuring system 46 and theoffset distance H3 are calculated according to a simulation of numericalvalues to be described later, and a test manufacturing of theparticle-measuring system to be mounted on an actual processing systemis carried out. Thus, particles are actually measured. In the evaluationof the actual measurement, when a result of the actual measurement isdifferent from a result of the simulation or when an expectedperformance has not been obtained, the basic system design is correctedor optimized based on the result of the evaluation. In other words, thedesign is reviewed including changes in the position of installing theparticle-measuring system 46, etc.

When a result of the actual measurement is satisfactory, theinstallation position of the particle-measuring system 46 and the offsetposition are reflected to a product (a processing system) on amanufacturing line.

The numerical simulation will be explained with reference to a flowchartshown in FIG. 5.

First, a calculation model (a mesh model) is prepared using computersoftware for calculation (for example, GAMBIT manufactured by FluentAsia Pacific Co., Ltd.). For example, a calculation expression forsetting boundary conditions (for example, a wall-surface temperature andpressure of the exhaust pipe, a kind of gas to be exhausted, etc.) isprepared based on the above-described basic system conditions (processconditions) using FLUENT of Fluent Asia Pacific Co., Ltd. Thiscalculation is carried out. A result of the calculation is reflected toan actual system (a test system). In other words, the particle-measuringsystem 46 is installed on a calculated position, and a result isevaluated. When the result is satisfactory, the result is reflected to adesign of a system to be manufactured.

As a result of this simulation, in the present embodiment, about 130 mmis determined as an optimum installation distance H2 from the exhaustopening 86 to the particle-measuring system 46 when a length H1 in avertical direction is 430 mm, for example, in the exhaust pipe 90 ofNW40.

For optimizing the position of installing the particle-measuring system46, the following are the essential conditions. That is, there is nowraparound of beams generated in the processing chamber, such as, forexample, heating beams (when the lamp heaters are the heating source) orplasma beams. There is space around for the installation, and that adensity of particles is relatively high in the exhaust pipe or a trackof an exhaust gas.

Particularly, the density of the flow of an exhausted film-forming gaswithin the exhaust pipe or the track of the exhaust gas is differentdepending on a kind of gas (a diameter and weigh of a particle), alayout shape of the exhaust pipe, a diameter of the exhaust pipe, anexhaust speed, weight, etc. Therefore, the density of particles is notnecessarily high at the center of the exhaust pipe. This will beexplained next.

Particles included in the exhaust gas flowing through the exhaust pipe90 are not uniformly distributed in the gas, but tend to be unevenlydistributed to an outside direction away from the center axis 92 of theprocessing chamber 48.

The reason is as follows. The film-forming gas supplied from theshowerhead 72 into the processing chamber 48 flows down and is dispersedstraight to the periphery of the processing chamber 48. The dispersedgas is then suctioned by each exhaust opening 86, and flows down throughthe exhaust pipe 90. Inertial force in a dispersion direction, that is,inertial force toward the outside in a radial direction of theprocessing chamber 48 applies directly to the particles.

Therefore, the particles included in the exhaust gas flowing downthrough the exhaust pipe 90 are unevenly distributed in an outsidedirection away from the center axis 92 as shown in FIG. 6. As a result,the density of the particles is highest at a point of the downwardoffset distance H3 from the center point O of the cross section, asshown in FIG. 3.

FIG. 6 shows one example of a model of the exhaust pipe within theprocessing chamber based on the above-described simulation, for example.Referring to FIG. 6, the film-forming gas ejected from the showerhead 72is collided against the surface of the wafer W and is dispersed to thesurrounding. The dispersed gas then flows down through the exhaust pipe90 via each exhaust opening 86. FIG. 6 shows a cross-sectional state ofthe distribution of the particles where the height H1 of the exhaustpipe 90 is 40 cm, a distance H5 from the bottom end of the exhaust pipe90 is 30 cm, and the inner diameter of the exhaust pipe is 40 mm.

In this example, the exhaust gas flows down through the exhaust pipe 90,with the inertial force applied straight to the exhaust gas toward theouter peripheral direction of the processing chamber 48. Therefore, thedensity of the exhaust gas is considered to be higher toward the outsideof the processing chamber within the exhaust pipe.

In this example, the exhaust gas flows down through the exhaust pipe 90,with the inertial force applied straight to the exhaust gas toward theouter peripheral direction of the processing chamber 48. Therefore, thedensity of the exhaust gas is considered to be higher toward the outsideof the processing chamber within the exhaust pipe. That is, the densityof the particles becomes higher on the outer side or the wall siderather than the center of the exhaust pipe; In the present embodiment,the exhaust pipe extends downwards from the bottom of the processchamber 48. Alternatively, the exhaust pipe may extend upwards from thetop of the chamber 48, horizontally from one side thereof, or slantwisefrom any part thereof. Simulation is performed on these alternativeembodiments, too.

Therefore, as shown in FIG. 3, the center of the detection direction ofthe scattered light detector 106 is directed outside to the center pointO of the cross section of the exhaust pipe. Instead, the center of thedetection direction of the scattered light detector 106 is directed to apoint P (this point P is a point where the density of the particles isapproximately the highest as described later) away outside from thechamber center axis 92 by a predetermined offset distance H3.

In this case, the directivity of the scattered light detector 106 has acertain level of an opening angle θ. When the scattered light detector106 is disposed at a position with a move by the offset distance H3, thescattered light detector 106 can detect with a high sensitivity in anarea where the density of the particles is approximately the highest.

Although a maximum value of the offset distance H3 depends on theprocess conditions, this value is about 0.75 times the radius of theexhaust pipe 90 as described later. Therefore, the center of thescattered light detector 106 is set at one point in an area within therange of an outside distance from the center point O of the crosssection to a point 108 shown by the distance H3.

In this example, when the diameter within the processing chamber 48 forprocessing an 8-inch wafer is about 440 mm and an internal diameter H4of the exhaust pipe 90 is about 40 mm, the offset distance H3 is set atabout 10 mm.

From the above, according to the present embodiment, as theparticle-measuring system 46 is installed on the exhaust pipe 90 at theupstream of the vacuum pump 98, the distance of a gas route between theprocessing chamber 48 and the installation position of theparticle-measuring system 46 becomes short. Therefore, the scatteredlight detector 106 can accurately detect the scattered lights SLgenerated based on the irradiation of the laser beams L onto theparticles P as shown in FIG. 3, without detecting unnecessary particlesirregularly generated.

As a result, it is possible to monitor the number of particles in highcorrelation with the actual volumes of particles within the processingchamber 48.

As shown in FIG. 3, according to the present embodiment, the laser beamsL irradiated by the laser beam irradiator 102 pass through the area inwhich the particles tend to be highly concentrated. Further, the laserbeams L are irradiated through the point P at which the particle densityis the highest. Further, the center of the scattered light detector 106is directed toward the point P at which the particle density is thehighest. Therefore, it is possible to efficiently irradiate the laserbeams L to the concentrated particles. Furthermore, it is possible toefficiently detect the generated scattered lights SL.

FIG. 7 is a graph showing a correlation between the actual number ofparticles within the processing chamber and the number of particlesmeasured by the particle-measuring system of the present embodiment. Inthis example, the diameter of particles that can be measured is 0.2 μmor above. The number of particles within the processing chamber has beenobtained by measuring the number of particles on the surface of a wafermonitored by a monitor installed within the processing chamber 42. Theprocess pressure is 0.7 Torr (93.3 Pa). As is clear from this graph, acorrelation coefficient R² of the correlation between both numbers is0.6894, and it has been confirmed that it is possible to obtain aconsiderably high value.

Accordingly, it is possible to detect the number of particles in highercorrelation with the actual number of particles within the processingchamber 48. In this case, as the directivity of the scattered lightdetector 106 has a certain level of the opening angle .theta., it isalso possible to detect the number of particles in a high correlationwhen the center of the scattered light detector 106 is directed to apoint deviated from the point P, for example, the center point O of thecross section.

As a result of simulations, FIGS. 8A to 8C show particle distributionswithin the exhaust pipe when the pressure inside the processing chamber42 is 0.7 Torr (93.3 Pa) and the film-forming temperature is 520° C.FIGS. 9A to 9C show particle distributions within the exhaust pipe whenthe pressure inside the processing chamber 42 is 4.5 Torr (599.8 Pa) andthe film-forming temperature is 580° C. As a film-forming gas, WF₆,SiH₂Cl₂ and Ar are used. In each of these drawings, a direction in whichthe processing chamber center axis 92 is positioned is set above.

As shown in FIGS. 8A to 8C, when the pressure inside the processingchamber 42 is 0.7 Torr (93.3 Pa), the particles are collected in arelatively higher concentration in a direction (downward in thedrawings) opposite to the direction in which the center axis 92 of theprocessing chamber is positioned. Particularly, the particles areconcentrated at a lower position than the center point O of the crosssection of the exhaust pipe. In other words, the particles arepositioned in an outside direction away from the center axis 92 of theprocessing chamber.

This trend is the same when the diameter of the particles is 0.2 μm(FIG. 8A), 0.5 μm (FIG. 8B), and 1.0 μm (FIG. 8C). In this case, adistance between the center point O of the cross section of the exhaustpipe and a point 110 where the particle density is the highest isapproximately 10 mm.

Further, as shown in FIGS. 9A to 9C, when the pressure inside theprocessing chamber 42 is 4.5 Torr (599.8 Pa), the particles are alsocollected in a relatively higher concentration in a direction (downwardin the drawings) opposite to the direction in which the center axis 92of the processing chamber is positioned. Particularly, the particles areconcentrated at a lower position than the center point O of the crosssection of the exhaust pipe. In other words, the particles arepositioned in an outside direction away from the center axis 92 of theprocessing chamber. This trend is the same when the diameter of theparticles is 0.2 μm (FIG. 9A), 0.5 μm (FIG. 9B), and 1.0 μm (FIG. 9C).In this case, a distance between the center point O of the cross sectionof the exhaust pipe and a point 112 where the particle density is thehighest is approximately 15 mm.

As explained above, the center point of the particle density is slightlyshifted downward in FIGS. 9A to 9C from those points shown in FIGS. 8Ato 8C.

As a result of carrying out a similar simulation for each particlematerial of WSi₂, C, and Al, approximately the same distributions havebeen obtained. As explained above, although it depends on the process,it is possible to efficiently detect scattered lights when a particlehigh-density area exists within an area sandwiched between the centerpoint O of the cross section of the exhaust pipe 90 and a point of abouta maximum 15 mm away downward from this center point O and also when thecenter of the scattered light detector 106 (reference FIG. 3) isdirected to within this area in each drawing. When the diameter of theexhaust pipe 90 is 40 mm (that is, the radius is 20 mm), the maximum 15mm corresponds to 0.75 times the radius.

In the present embodiment, the laser beams L irradiated from the laserbeam irradiator 102 have been set in a direction toward the center axis92 of the processing chamber through the center point O of the crosssection of the exhaust pipe 90. However, the setting of the laser beamsL is not limited to this. The laser beams L may be set in any directionwhen the laser beams L are set to transmit through the area in which theparticle density is high.

For example, as shown in FIG. 10, the laser beam irradiator 102 is setso that the laser beams L can be transmitted through a point P that is aposition with a predetermined offset distance H6 from the center point Oof the cross section of the exhaust pipe 90 to a direction opposite tothe direction in which the center axis 92 of the processing chamber ispositioned. In this example, the irradiation direction of the laserbeams L is along a direction approximately orthogonal with a directionfrom the center point O of the cross section to the center axis 92 ofthe processing chamber. The scattered light detector 106 is set in adirection approximately orthogonal with the irradiation direction of thelaser beams L. The center of the scattered light detector 106 isdirected toward the point P where the density of the particles is high.As described above, a maximum value of the offset distance H6 from thecenter point O is 0.75 times of the radius of the exhaust pipe. In thiscase, the offset distance H6 is set to about 12 mm, for example.

When the irradiation direction of the laser beams L passes through anarea between a center point O (91) of the cross section and a point P(114), this direction is not particularly limited. For example, as shownin FIG. 11, the laser beams L may be irradiated from an inclineddirection as compared with the direction shown in FIG. 10. A measurementof particles carried out based on the example of the particle-measuringsystem shown in FIG. 10 has been evaluated, and a result of thisevaluation will be explained with reference to FIGS. 12 and 17.

FIG. 12 is a graph showing an evaluation result of a measurement of thenumber of particles by passing the laser beams L through the point (thepoint P) where the density of the particles within the exhaust pipe ishigh, using the particle-measuring system according to the embodimentshown in FIG. 10. FIG. 17 is a graph showing an evaluation result of ameasurement of the number of particles by passing the laser beams Lthrough the exhaust pipe 90 using the conventional particle-measuringsystem shown in FIG. 18. In both cases, the particles measured have adiameter of 0.23 μm or above.

According to the present embodiment, a correlation coefficient R₂becomes 0.7864 as shown in FIG. 12, which is a very high satisfactoryvalue. On the other hand, according to the conventionalparticle-measuring system, a correlation coefficient R₂ becomes 0.0031as shown in FIG. 17, which is a very low value.

It has been confirmed that it is possible to obtain a substantiallyimproved high coefficient of correlation when laser beams have beenpassed through the portion where the density of particles is high likethe present embodiment.

In the above description, a film-forming system has been explained bytaking a lamp-heating system as an example. However, the film-formingsystem is not limited to this. It is needless to mention that thepresent invention can also be applied to a resistor-heating typefilm-forming system or a system using plasma. A film-forming systemhaving a heating lamp, according to the invention, has been described.Nonetheless, the invention is not limited to a film-forming system ofthis type. The invention can be applied to a film-forming system havinga heating resistor and a film-forming system using plasma. Further, canbe applied to other various processing systems such as anoxidation-diffusion system, an etching system and an annealing system.Still further, the invention can be applied to an exhaust system, suchas a load lock, for use in a processing system. Further, an object to beprocessed is not limited to a semiconductor wafer. An LCD substrate, aglass substrate, etc. can also be processed.

As explained above, according to the processing system of the presentinvention, it is possible to exhibit the following excellent operationeffects.

According to the present invention, as the particle-measuring system isinstalled on the exhaust pipe at the upstream of the vacuum pump, thedistance of the gas flowing route between the processing chamber and theparticle-measuring system is very short.

Therefore, unlike the conventional processing system, it is possible toavoid measuring abnormalities that fall from the inner walls of thepipes, blades of the vacuum pump and walls. Instead, it is possible toobtain a high correlation between the actual number of particles withinthe processing chamber and the values measured by the particle-measuringsystem.

Further, when the irradiation direction of the laser beams L is set tofollow the direction connecting between the center point of the exhaustpipe and the center axis of the processing chamber, it is possible toirradiate the laser beams onto the portion where the density of theparticles is high. Therefore, it is possible to grasp an accurate volumeof particles, with a further increased correlation.

Further, when the center of the scattered light detector is offset in apredetermined direction by a predetermined distance from the centerpoint of the cross section of the exhaust pipe, namely, in a radialoutside direction away from the center point or on the wall side, it ispossible to direct the center of the scattered light detector to aportion where the density of the particles is high. As a result, it ispossible to further increase the correlation.

Further, when the laser beams are transmitted to a position offset by apredetermined distance from the center point of the cross section of theexhaust pipe in a specific direction, namely, in the radial outsidedirection away from the center point or on the wall side, it is possibleto irradiate the laser beams L to a portion where the density of theparticles is high. As a result, it is possible to increase thecorrelation.

FIG. 13 shows an example of a configuration of a particle-measuringsystem that can rotate around the piping installed, as a secondembodiment of the present invention. In the configuration shown in FIG.13, portions equivalent to those in FIG. 1 are attached with identicalreference numbers, and their detailed explanation will be omitted.

A particle-measuring system 110 is installed on an exhaust pipe 90 in asimilar manner to that of the particle-measuring system 46.

This particle-measuring system 110 consists of a stopper member 114disposed opposite to a laser beam irradiator 112, and a scattered lightdetector 116 made of a light-receiving element or the like provided onthe pipe wall in a direction approximately orthogonal with anirradiation direction of laser beams L, as shown in FIG. 14A. FIG. 14Bis a diagram showing a configuration of a cross-sectional surface of theparticle-measuring system 110 cut along a line D-D in FIG. 14A.

This laser beam irradiator 112 is disposed at the outside (atmosphereside) of a window 120 made of a transparent material provided inairtight in a radial direction of a manifold 118. A guiding mechanism122 is provided along the window 120. The laser beam irradiator 112 ismoved within the guiding mechanism 122 by a driver 124 having a motor ora linear motor.

The manifold 118 is formed using one of stainless steel, aluminum,aluminum alloy, or aluminum or aluminum alloy of which surface has beenalumite processed. The window 120 is made of quartz glass orcorrosion-proof sapphire glass or the like. Windows to be describedlater are also made of a similar material.

The stopper member 114 is also disposed at the outside of a window 128,and is always moved by a driver 132 having a motor or a linear motor toa position where laser beams irradiated by the laser beam irradiator 112are received along a guiding mechanism 130.

The scattered light detector 116 is also moved in two-dimensionaldirections (up/down and left/right directions) so as to be basically ina position orthogonal with a direction of laser beams irradiated by thelaser beam irradiator 112 at the outside of a window 134 provided on themanifold 118. The scattered light detector 116 is also moved to aposition not orthogonal with laser beams in order to measure the numberof particles at a position where the density of particles is high. Thescattered light detector 116 is moved in two-dimensional directions onthe window 134 by a driver 138 having a motor or a linear motor in anarea encircled by a guiding mechanism 136.

As shown in FIG. 13, the particle-measuring system 110 is constructed torotate along a radial direction of the exhaust pipe 90. Specifically,known magnetic fluid vacuum seals 140 for maintaining a vacuum state aredisposed on both-end flanges, and each magnetic fluid vacuum seal 140 isfitted with the particle-measuring system 110 so as to be rotatablearound the exhaust pipe 90. A rotary driver 142 executes this rotation.For example, this rotation may be carried out as follows. A gear isprovided at the side of the exhaust pipe 90. A motor is connected tothis gear to have an engagement with this gear. Thus, the wholeparticle-measuring system 110 is rotated based on the rotation of themotor. Alternatively, the particle-measuring system 110 may be rotatedby magnetic force of a magnet.

For carrying out a positional adjustment of the laser beam irradiator112, the stopper member 114 and the scattered light detector 116respectively, a position sensor not shown is provided for each unit todetect positions. A position adjuster 144 drives each driver accordingto a detected position signal. Data based on a simulation may be inputto this position adjuster 144 to retrieve an optimum point.

One example of a particle distribution state according to the computersimulation will be explained with reference to FIG. 15.

This simulation shows an example of exhausting a process gas ofWF₆/DCS/Ar:4/150/450 sccm in a WSi process, with 0.7 Torr (93.3 Pa) foran internal pressure of the chamber by taking the weight intoconsideration. This shows a state of a result of data that a distance H3from the center of a bent exhaust pipe connected to an assembling pipeis 300 mm.

As shown in FIG. 16, the data of this simulation is input to theposition adjuster 144 to drive each driver. In this example, the laserbeam irradiator 112 and the stopper member 114 are moved so that thelaser beams of the laser beam irradiator 112 pass through the area inwhich the density of particles is highest. The scattered light detector116 is moved to a position orthogonal with the laser beams.

The controller/processor 41 controls the laser beam irradiator 112 andthe scattered light detector 116 to input measured data of particles andcarry out an arithmetic processing. The control and process section 41may be provided in or outside the system control section that controlsthe entire processing system. The display 43 is provided to make adisplay of processing results and expressions and various parameters tobe used for simulations.

For example, it is possible to control and manage thecontroller/processor 41 and the position adjuster 144 by software byconnecting these units to a user-operable controller such as a personalcomputer not shown.

Depending on the shape of the exhaust pipe, and also when there is amounting table or an exhaust porous plate in front of the exhaustopening to hinder the flow of a gas, these obstacles affect the gas flowdistribution within the exhaust pipe, and also affect the particledensity.

Therefore, according to the present embodiment, a simulation is carriedout based on parameters relating to the processing unit and themanufacturing process. Based on a result of data obtained from thesimulation, the position adjuster 144 automatically moves the laser beamirradiator 112, the stopper member 114, and the scattered light detector116, thereby to irradiate laser beams to a portion where the density ofparticles is the highest. Thus, the number of particles can be measuredin a satisfactory condition. Particularly, it is possible to carry out asimulation and an actual measurement according to a kind of particles,or a kind of an exhaust gas including these particles, or a speed ofexhausting the gas. As a result, it is possible to set an optimummeasuring position.

Therefore, it is possible to find an optimum measuring point based onactual situation of measuring instead of the measuring at a constantdesign time. Thus, it is possible to obtain high degree of freedom ofmeasuring and to achieve accurate measuring.

FIG. 20 is a view showing a structural example of a processing systemaccording to a third embodiment having a particle measuring portionmounted thereon, FIG. 21 is a block diagram showing a cleaning end pointdetermination portion, and FIG. 22 is an explanatory view forillustrating the principle of determining an end point of the cleaningprocessing. In description of this embodiment, like reference numeralsdenote constituent parts shown in FIGS. 20 and 21 which are equivalentto those depicted in FIG. 1, thereby omitting the detailed explanationthereof. Further, reference is made to the positional relationshipbetween a transmission window and an exhaust opening in the processingchamber shown in FIG. 2 and an attachment state of the particlemeasuring portion illustrated in FIG. 3.

In the third embodiment, description will be given taking a CVD systemas an example of the processing system. Naturally, this can be likewiseapplied to all processing systems that require cleaning processing usinga sputtering device, an etching device and others. Furthermore, althoughreference is made to a system having a structure as disclosed inJapanese patent application laid-open No. 2001-59808 proposed by thepresent applicant as a concrete example of a CVD system and particlemeasuring portion, this is equivalent to the first embodiment mentionedabove except for the structures of a gas introducing system and a waferattachment system.

As shown in FIG. 20, this CVD system 151 is roughly constituted by aprocessing unit 42 which performs film-forming processing to a wafer Wand an exhaust system 44 which exhausts an atmosphere or a film-forminggas in the processing unit 42.

There is provided a particle measuring system 46 which measures thenumber of particles in the exhaust gas flowing through the exhaust gas44. This particle measuring system 46 is controlled by acontroller/processor 41. This controller/processor 41 may beincorporated in a system control portion (not shown) which controls theentire processing system or may be an independent device. Moreover, alater-described cleaning end point determination system 152 is connectedto this particle measuring system 46.

An annular reflector 50 having the inner surface mirror-finished with amaterial which reflects a heat ray is arranged below the inside of theprocessing chamber 48 of the processing unit 42. A support column 84 isprovided on the outer periphery of the reflector 50, and a mountingtable 52 which attaches the wafer W is supported above this columnthrough an attachment 60. Lifter pins 54 (only two are shown in theillustrative example) which lift up the wafer W from the lower surfacethereof are arranged below the mount base 52 through lifter pin holes 50and they are driven up and down by a non-illustrated drive system. Thiswafer W is transferred between a carriage mechanism having anon-illustrated arm, etc., and the mounting table 52 and carried into orfrom the processing chamber.

One end of an integral rod-shaped clamp support portion 155 is attachedto the lifter pin 54. A clamp ring 156 is attached to the other end ofthe clamp support portion 155, and the peripheral edge portion of thewafer W is pushed and fixed so as to be appressed against the mountingtable 52. A space between the processing space S and the lower side ofthe mounting table 52 becomes substantially airtight, and the wraparoundof the film-forming gas to the back side of the wafer W or the back sideof the mounting table 52 can be avoided, thereby preventing anunnecessary film from being formed.

In addition, a heating chamber 64 is provided on the bottom of theprocessing chamber directly below the mounting table 52 through atransmission window 62. A plurality of heating lamps 66 are attached toa rotary table 68 which also serves as a reflecting mirror in theheating chamber 64. This rotary table 68 is rotated by a motor 70. Thisrotation can uniformly heat the back side of the wafer W. It is to benoted that a resistance heater as a heating source may be embedded inthe mounting table 52.

Additionally, a shower head portion 157 having many gas injection holes158 formed thereto is provided to a processing chamber ceiling portionopposite to the mounting table 52. This shower head portion 157 ismolded into a circular box shape by using, e.g., aluminium.

This shower head portion 157 is connected to a non-illustrated gasintroducing system and has gas introducing openings 159, 160 and 161 forsupplying the gasses provided thereto. Further, the film-forming gassessupplied from each of the two gas introducing openings 159 and 160 ofthese openings are mixed in a gas mixing portion 162 by rectificationplates 162 a, 162 b and 163 c laminated in the form of three layers, andled into a diffusion chamber 163 below the gas mixing portion 162.

Furthermore, a diffusion plate 164 having many diffusion holes isprovided in the diffusion chamber 163, and the introduced mixed gas isdiffused. Moreover, a cleaning gas supply pipe 165 is connected to theremaining gas introduction opening 161. The cleaning gas supply pipe 165may be used by being commonly connected to one of the gas introducingopenings 159 and 160 through a valve. This cleaning gas supply pipe 165is connected to a flow rate controller 167 through an opening/closingvalve 166. In the cleaning processing, a cleaning gas, e.g., a ClF₃ gasis caused to flow. Each gas supplied from each of the gas introducingopenings 159, 160 and 161 of the shower head portion 157 flows into thediffusion chamber 163 in the shower head portion 157, is diffused by thediffusion plate 164, introduced into the gas diffusion chamber 168 froma gas discharge hole 164 a formed in the diffusion plate 164, anddiffused and injected into the processing space S from a plurality ofgas injection holes 158 formed in a shower plate 169.

As shown in FIGS. 36 and 37, the shower head portion 157 whichintroduces the process gas is arranged on the upper portion of theprocessing chamber. The shower head portion 157 is constituted by anon-illustrated shower base, a gas introducing plate 401, a shower plate169 and a non-illustrated gas mixing portion 162.

The gas mixing portion 162 which introduces the process gas is connectedto the upper side of the gas introducing plate 401 arranged at thelowermost end, and the gas introducing plate 401 thereof is connected soas to be fitted to the upper part of the shower base on the innerperipheral side.

A concave portion 409 is formed at the center of the gas introducingplate 401, and a rectification plate 405 having a cylindrical shape witha lid fitted to the upper part of the gas introducing plate 401, a lowerplate (rectification plate 163 c), a middle plate 403 (rectificationplate 162 b) and an upper plate 404 (rectification plate 162 a) areprovided so as to be fitted in a casing 431. As shown in FIG. 37, thegas introducing plate 401 and the casing 431 are fastened by a pluralityof bolts 430 through a sealing member 429 and air-tightly fixed. Theupper part of the casing 431 has gas introducing openings 424, 425 and426.

FIG. 37 is a cross-sectional view showing a structure of the inside ofthe casing 431 of the gas introducing portion. To the upper plate 404are provided a duct 421 which communicates with the cleaning gasintroducing opening 425 of the casing 431, a duct 427 which communicateswith the first main gas introducing opening 424 of the casing 431, and aduct 423 which communicates with the second process gas introducingopening 426 of the casing 431.

The duct 427 which communicates with the first process gas introducingopening 424 communicates with a groove 418 formed at the center of themiddle plate 403 through a groove 415 provided at a semi-circumferentialportion of the middle plate 403 on the outer peripheral side, and slitsare formed in a plurality of vertical directions to a convex portion 417which protrudes so as to facilitate mixing the gas in the groove 418,and they continuously communicate with the duct 421 of the upper plate404 and the grooves 418 and 412 of the middle plate 403 and the lowerplate 402.

In addition, the duct 423 communicating with the second process gasintroducing opening 426 communicates with a groove 412 formed at thecenter of the lower plate 402 through a groove 411 provided at thesemi-circumferential part of the lower plate 402 on the outer peripheralside via the duct 416 provided to the middle plate 403, slits are formedin a plurality of vertical directions to a convex portion 413 whichprotrudes so as to facilitate mixing of the gas in the groove 412, andthey communicate with a space between the lower plate 402 and therectification plate 405.

This space communicates with the main gas duct 407 through a space 409formed by the gas introducing plate 401 and the rectification plate 405via an open hole 410 of the rectification plate 405. With such astructure, an H₂ gas and a WF₆ gas or the like are sufficiently mixed inthe groove 412, and the mixed gas is uniformly supplied into theprocessing chamber 48 from the shower head portion 157 through theprocess gas duct 407.

Additionally, a cavity may be provided to the upper plate 404 so as tocommunicate with the outer peripheral side of the shower plate 169 sothat the H₂ gas is supplied from a peripheral gas introducing hole tothe periphery. In the gas mixing portion 162, when H₂, SiH₄ and N₂gasses are supplied to the first process gas introducing opening 424 andWF₆, and Ar and the like are supplied to the second process gasintroducing port 426, these gasses are mixed and are supplied from themain gas duct 407 into the shower head portion 157 as described inconnection with FIG. 37. Further, the ClF₃ gas supplied to the cleaninggas introducing opening 425 is supplied into the shower head portion 157through the cleaning gas duct 418 formed at the center of the upperplate 404 and via the slits of the convex portion 417 of the middleplate 403, the slits of the convex portion 413 of the lower plate 402and the main gas duct 407.

Then, the first and second process gasses supplied to the main gas duct407 are mixed, diffused in a second space portion 168 after passingthrough a plurality of gas discharge openings formed in therectification plate 164 from the first space portion 163 in the showerhead portion 157, and uniformly discharged toward the wafer W from theplurality of gas discharge holes 158 formed in the shower plate 169.Furthermore, the cleaning gas ClF₃ gas used to remove an unnecessaryfilm adhered to the inner wall and the like of the processing chamber 48is supplied to the cleaning gas duct 418 and, like the process gas,passes through a plurality of gas discharge holes formed in therectification plate 164 from the first space portion 163 in the showerhead portion 157, is diffused in the second space portion 168,discharged from the plurality of gas discharge holes 158 formed in theshower plate 169 and removes the unnecessary film which has adhered inthe processing chamber.

Each gas is uniformly diffused in the second space portion by increasingthe pressure in the first space portion 163 more than that in the secondspace portion 168 and reducing the conductance of the rectificationplate 164 less than that of the shower plate 165.

Moreover, a rectification plate 82 is provided on the outer peripheralside of the mounting table 52. The rectification plate 82 has aring-like shape and a plurality of rectification holes 80 formed theretoand is supported in the vertical direction by an annular support column84. In addition, a through hole 84 a is opened on the side wall of thesupport column 84, and a relief valve 168 is attached so as to cover thethrough hole 84 a, thereby adjusting the pressure between the upper andlower parts of the wafer W in the chamber. This pressure adjustmentprevents jounce of the wafer W from being generated due to the pressuredifference between the pressure under the mounting table 52 and theprocessing space S when carrying in/out the wafer W. Additionally, aplurality of exhaust openings 86 are provided on the bottom of thechamber below the rectification plate 82.

As shown in FIG. 20, four exhaust openings 86 are arranged atsubstantially even intervals along the circumferential part of thebottom, and exhaust ports 88 are provided for each exhaust opening 86.

Further, the exhaust openings 86 may be provided at the center of thebottom of the processing chamber 48.

These exhaust ports 88 are air-tightly connected to the respectiveexhaust pipes 90. Like the first embodiment, one or a plurality ofexhaust pipes 90 are used to provide a particle measuring system 46 inthe middle of the route to a collecting pipe 100.

A film-forming process using the CVD system will now be described.

The film-forming process is substantially equivalent to that of thefirst embodiment mentioned above, and description will be given to partshaving different effects in this embodiment but description on otherparts will be simplified.

The wafer W is delivered into the lifted lifter pin 54 in the processingchamber 48 by a non-illustrated carrying arm from an opened gate valveG, the carrying arm is then retracted, and the gate valve G is closed.

Also, the lifter pin 54 is moved down and the wafer W is mounted on themounting table 52. Further, the outer peripheral edge part of the waferW is pressed with the inner peripheral edge part of the clamp ring 156.Thereafter, the air in the processing chamber 48 is exhausted by theexhaust system 44. At this moment, the relief valve 168 is actuated anda difference between the pressure below the mounting table 52 and thepressure on the wafer W side is decreased. As a result, jounce of thewafer W generated in exhaust is avoided, and occurrence of particles isrestricted.

Then, various kinds of gasses for the process gas are introduced intothe processing chamber 48, the exhaust system 44 is adjusted to set apredetermined degree of vacuum, and a temperature of the wafer W isincreased to a predetermined value, e.g., 350 to 700° C. and maintainedby a heating lamp 66 which rotationally moves. As a result, apredetermined chemical reaction occurs in the film-forming gas, and athin film is deposited and formed on the surface of the wafer W.

In this structure, the particle measuring system 46 measures the numberof particles included in the exhaust gas which passes through theexhaust pipe 90.

When a process of the wafer W is continuously or intermittently carriedout, a command to perform the cleaning process is issued from a systemhost computer 153 in accordance with a predetermined cleaning schedule.

This cleaning process is carried out by introducing the ClF₃ gas intothe processing chamber 48 through the cleaning gas supply pipe 165. As aresult, an unnecessary film which has adhered to the inner wall of theprocessing chamber 48 or the internal structure in the chamber, e.g.,the surface of the mounting table 52, the clamp ring 156, the showerhead portion 157, etc., is removed. Furthermore, in order to obtain thejust etch in the above-described cleaning process and determine the endpoint even in the middle of the cleaning process, the number ofparticles included in the exhaust gas is measured by the particlemeasuring system 46.

Description will now be given as to the particle measuring system 46 andthe cleaning end point determination device 152.

As shown in FIG. 3, this particle measuring system 46 is constituted bya laser beam irradiator 102, a stopper member 104 and a scattered lightdetector 106. As a laser element in the laser beam irradiator 102, asemiconductor laser element such as a minimized GaAlAs or the like isused, and an output of several W to several tens of W is preferable asan output therefrom. It is to be noted that a YAG laser with a highoutput can be used as the semiconductor laser element.

Although a laser beam L emitted by this laser bean irradiator 102 isemitted at the center of the cross section of the exhaust pipe 90, it ispreferably emitted so as to be parallel to a line segment connecting thecenter point O of the cross section and the central axis of the chamber92 as shown in FIG. 3 like the first embodiment mentioned above.Moreover, the scattered light detector 106 is provided on the pipe wallin a direction substantially orthogonal to the irradiation direction ofthe laser beam L, and it receives the scattered lights SL generated whenthe laser beam L is emitted on the particle P.

This scattered light detector 106 outputs a detection signal to thecontroller/processor 41. This controller/processor 41 counts the numberof particles per unit time. As this unit time, 0.1 seconds or above canbe set, but 2 seconds is set in this example. When the unit time is setto 2 seconds, the number of particles is measured every 2 seconds. Ofcourse, this unit time can be freely set according to need. The numberof particles obtained every 2 seconds is outputted to the cleaning endpoint determination portion 152 as a measured value.

The cleaning end point determination device 152 outputs a direction ofthe end point to the system host computer 153 which controls the entireCVD system. The system host computer 153 controls, e.g., anopening/closing valve 166. It is to be noted that a control systemhaving a parameter to be controlled incorporated therein in advancemaybe provided in place of the system host computer 153. As to thisparameter, constituent parts such as a film thickness measurement, apressure gauge, a film-forming gas density and component and a filmquality measurement can be provided and an optimum film forming methodcan be carried out based on the respective measurement results.

Then, the cleaning end point determination device 152 will now bedescribed with reference to FIGS. 21 and 22.

As shown in FIG. 22, when the ClF₃ gas is introduced into the processingchamber 48 and the cleaning process is started, a large quantity ofparticles due to etching is generated after a while and exhausted to theexhaust pipe 90 together with the gas. Then, at a point in time thenumber of particles is reduced to substantially a few, this is the justetch timing, as will be described later. This timing is automaticallydetected, and the end point of the cleaning process is determined basedon this.

As shown in FIG. 21, the cleaning end point determination device 152 isconstituted by a particle number judgment portion 171, a low particlenumber duration measuring portion 172, a just etch timing determinationportion 173, an over-etching period determination portion 174, an endpoint determination portion 175 and a control portion 176 each of whichwill be described later.

The above-described controller/processor 41 measures the number ofparticles at intervals of, e.g., 2 seconds as a unit time in thisembodiment. Naturally, the unit time can be appropriately set inaccordance with situations and the like. The obtained measured value isoutputted from the controller/processor 41 to the particle numberjudgment portion 171.

The particle number judgment portion 171 receives the measured valuefrom the controller/processor 41 and judges whether this measured valueis not more than a predetermined judgment value, e.g., 10/2 seconds. Itis to be noted that this judgment value is not restricted to aparticular value and an arbitrary value can be appropriately set.Incidentally, the size of the particle to be measured can be selectedwithin a range of not less than 0.001 μm in many ways by selectivelysetting a parameter by the controller/processor 41.

The judgment result is inputted to the low particle number durationmeasuring portion 172 on the next stage. This low particle numberduration measuring portion 172 measures a time during which the statethat the number of particles is not more than the judgment value, e.g.,10 is continued, and outputs the measured result (duration) to the justetch timing determination portion 173.

Then, the just etch timing determination portion 173 determines the justetch timing based on the inputted duration. As shown in FIG. 22, thisdetermination decides whether the duration of the low particle number iscontinued for a predetermined threshold value, e.g., 16 seconds(corresponding to 8 unit times with respect to the unit time mentionedabove) or above. When the duration reaches this threshold value orabove, a point in time obtained by tracing back for the time of thethreshold value, i.e., 16 seconds from that moment is determined as ajust etch time. It is to be noted that a point in time when the time ofthe threshold value, i.e., 16 seconds has passed may be determined asthe just etch time. Incidentally, 16 seconds as the threshold value isjust an example, a range of, e.g., 1 to approximately 300 seconds isassumed, and the threshold value can be appropriately set from thisrange. Of course, the threshold value is not restricted to this range.

In addition, the over-etching period determination portion 174determines an over-etching period to be subsequently carried out basedon a cleaning process period T from the start of etching to the justetch timing. This over-etching period determination portion 174determines an over-etching period by multiplying the cleaning processperiod T by a predetermined coefficient k. Although this coefficient kis predetermined based on cleaning conditions, such as the type ofdeposited film, temperature, quantity of flow of the cleaning gas andothers, a range of approximately 0.1 to 1 is usually assumed, and itpreferably falls within a range of 0.2 to 0.6. Here, the coefficient kis set to, e.g., k=0.5.

Additionally, the end point determination portion 175 determines thefinish time of the over-etching period as an end point (finish time) ofthe cleaning process. That is, the time obtained by adding theover-etching period (k•T) to the time of the just etch timing is thecleaning process finish time. In order to stop supply of the cleaninggas when the end point is reached, the system host computer 153 performscontrol to close the opening/closing valve 66. This cleaning end pointdetermination device 152 is constituted by, e.g., a microcomputer andthe like, and the operation of each constituent part is controlled bythe controller 176 in accordance with a predetermined program.

As shown in FIG. 22, although particles are hardly generated for a whileafter starting supply of the ClF₃ gas which is the cleaning gas, theoperation to determine the end point of the cleaning process mentionedabove is controlled to be started after the particle number higher thana threshold value of the particle number is once detected. Here,referring to FIGS. 23A and 23B in which the correlation between the justetch timing and increase/decrease in the particle number is actuallyexamined, the experiment results will now be described.

FIG. 23A shows increase/decrease in the particle number when performingthe cleaning process after carrying out the film-forming process of aWSi film to five wafers, and FIG. 23B shows increase/decrease in theparticle number when performing the cleaning process after carrying outthe film-forming process of the WSi film to 25 semiconductor wafers.However, in these drawings, scales of the vertical axis are different.Further, a numeric figure of the time in the horizontal axis representshours, minutes and seconds.

Here, ClF₃ gas is used as the cleaning gas, and the just etch timing isdetermined by visually confirming a change in color of the mountingtable. That is, a point in time when the surface of the mounting tablein the processing chamber is observed from an observation window on thechamber wall and a color of the surface of the mounting table is changedis determined as the just etch timing.

As shown in FIGS. 23A and 23B, when the ClF₃ gas is supplied into theprocessing chamber 48 and the cleaning process is started, the particlesare hardly generated for approximately 50 seconds. This can beconsidered as a time lag until the cleaning gas is introduced into theprocessing chamber 48 after the opening/closing valve 166 (see FIG. 21)for the cleaning gas is “opened”.

Then, the particles are suddenly generated when approximately 50 secondspass, and they are then decreased after a peak is once reached. At thismoment, in case of processing the 25 wafers shown in FIG. 23B, a largepeak value is once suddenly detected. Thereafter, the particles aregreatly reduced for approximately 10 seconds, and the particle number isagain increased and a second peak is reached. After this peak, theparticle number is gradually decreased.

In this manner, a measuring pattern differs depending on a thickness ofan adherent film. Here, in the etch timing determination portion 174, asdescribed in connection with FIG. 21, a point in time when the detectionstate that the particle number per unit time (2 seconds) is not morethan 10 is continued for 16 seconds is determined as a just etch timing,for example. Therefore, this just etch timing is the time obtained bytracing back from that moment.

As a result, in FIG. 23A, the time of the just etch timing is afterelapse of 57 seconds from start of cleaning in the case of visualconfirmation, and it is after elapse of 54 seconds in the case of theparticle measuring system 46, and their difference is just 3 seconds.

Furthermore, in FIG. 23B, the time of the just etch timing is afterelapse of 135 seconds from start of cleaning in the case of visualconfirmation, and it is after elapse of 134 seconds in the case of theparticle measuring system 46. Their difference is just 1 second, thesubstantial correlation is obtained based on this.

As described above, the just etch timing determined by using theparameter measuring system 46 is substantially the same as thatdetermined by visual confirmation, and it can be confirmed that the justetch timing is appropriately and automatically determined. That is, thetime at which the particles are generated due to etching afterintroducing the cleaning gas can be measured irrespective of anaccumulation number of wafers processed in the processing chamber, andthe over-etching timing can be automatically and correctly determined.

Therefore, by applying the over-etching process in the calculatedover-etching period with the just etch timing being determined as astart time, an appropriate cleaning process can be realized. That is,the appropriate cleaning process can be constantly executed byperforming setting in the system host computer or an APC (AdvanceProcess Control) control system in advance without effecting theoperation and the like by an operator, irrespective of the number ofwafers processed in the processing chamber 48.

The process to determine an etching end point will now be described withreference to FIG. 24.

When a command to start the cleaning process is issued by anon-illustrated host computer and the like, the cleaning program isstarted (step S1), and supply of the cleaning gas into the processingchamber 48 (see FIG. 20) begins (step S2). With this start, measurementof an elapsed time of the cleaning process begins.

Subsequently, a judgment is made upon whether an initial time t1 (seeFIG. 22) has elapsed after start of supply of the cleaning gas (stepS3). That is because the particles are not generated immediately afterstart of supply of the cleaning gas, but the particles are not generatedfor a while even though the cleaning gas is supplied into the processingchamber, and measurement of the particles in this period is avoided.This initial time t1 is, e.g., approximately 1 to 120 seconds dependingon a quantity of the cleaning gas to be supplied and the like. It is tobe noted that problems do not occur even if the particle measurement iscarried out during this initial time t1 as long as the arithmeticoperation is not performed based on a measured value which will bedescribed later.

Moreover, when the initial time t1 has elapsed, measurement of theparticle number in the exhaust gas is started by the particle measuringsystem 46 (step S4). At this moment, namely, at a point in time when theinitial time t1 has elapsed, as shown in FIG. 23, a sufficiently largequantity of particles is generated by the cleaning process. Thus, as ameasured value of the particle number at this moment, a measured valuefar greater than 10 which can be assuredly a threshold value isoutputted. This measured value is inputted to the particle numberjudgment portion 171, and a judgment is made upon whether the particlenumber is not more than 10 (step S5).

Subsequently, a result of this judgment is inputted to the low particlenumber duration measuring portion 172. When the particle number is notmore than 10 (YES), a judgment is made upon whether the particle numberof the precedent measured value is also not more than 10 (step S6). Onthe other hand, if it is not more than 10 (NO), measurement is continuedas it is.

If the precedent particle number is not more than 10 (YES) in thejudgment at the step S6, the processing advances to a step S7 which willbe described later. If the particle number of the precedent measuredvalue exceeds 10 (NO), this means the particle number becomes lower thanthe threshold value at this moment. Therefore, it is considered thatthere is the possibility that this point in time becomes the just etchtime, and the elapsed time after start of supply of the cleaning gas toa current point in time is stored as a cleaning process period T (stepS7). This elapsed time T is updated to a time (period) when the particlenumber becomes not more than 10 last time if the measured value of theparticle number is in the vicinity of 10 which is the threshold value.

Then, a judgment is made upon whether the state that the particle numberis not more than the threshold value (10) is continued for a set time(step S8). Here, the set time is set to 16 seconds which is a thresholdvalue. In this judgment, if the low particle number duration that ameasured value of the particle number is not more than 10 is 16 secondsor below (NO), the processing returns to the step S5, and measurement ofthe particle number is continued. In other words, the low particlenumber duration that the measured value of the particle number is notmore than 10 is measured by the low particle number duration measuringportion 172 and the just etch timing determination portion 173 at thesteps S5 to S8. On the other hand, if the low particle number durationis continued for the set time (16 seconds) (YES), a point in timeobtained by tracing back from that time for 16 seconds is determined asthe just etch timing (step S9).

Then, the cleaning process timing to the moment obtained by harking backfor 16 seconds becomes the stored time T. It is to be noted that a pointin time that the low particle number state is continued for 16 secondsmay be set as the just etch timing without harking back 16 seconds asmentioned above. Based on this result, the over-etching perioddetermination portion 174 determines an over-etching period by executing(cleaning process period T×k) (step S10).

Moreover, based on this over-etching period, the end point determinationportion 175 determines an end point of the etching process (etchingfinish time) (step S11). In addition, if this etching point is reached(step S12), supply of the cleaning gas is stopped (step S13), and theover-etching process is terminated. That is, the cleaning process isterminated. It is to be noted that the size of the particles to bemeasured here can be selected within a range of 0.001 μm or above inmany ways by selectively setting a parameter in the controller/processor41.

As described above, an appropriate and substantially correct just etchtiming can be obtained irrespective of the number of wafers processed inthe processing chamber 48 before starting the cleaning process.Additionally, an end point of the cleaning process can be determinedfrom this just etch timing. By setting a series of these sequences or aparameter in the system host computer or the APC control system inadvance, an adequate cleaning process can be constantly automaticallycarried out without the operation by an operator. Therefore, damage tothe inner wall of the processing chamber or its internal structure canbe reduced when carrying out cleaning processing, and the duration oflife of the chamber or the internal structure can be prolonged. Further,since only a necessary quantity of the expensive cleaning gas is used,wasteful consumption can be avoided.

In this embodiment, although description has been given as to an exampleof the WSi film as the unnecessary film which should be removed by thecleaning process, the present invention is not restricted thereto, andthe cleaning process method according to the present invention can beapplied to any film type. For example, the present invention can beapplied to the cleaning process to films of Ti, W, WN, TiN, Ta, TaOx,SiO₂, SiN, SiON, TaN, HfO₂, ZrO₂, PaO₃ and the like. Furthermore, thecleaning gas is not restricted to ClF₃ gas, and any other cleaning gassuch as NF₃, ClF, HF and others can be applied to the present invention.Moreover, the present invention can be applied to an end point of plasmacleaning. In addition, the present invention can be applied to an endpoint of plasma cleaning. As a plasma source, it is possible to apply toa plasma processing system of, e.g., a capacitance type (parallelplate), an ICP, a helicon wave, a micro wave (radial line slot antennatype) and the like. Here, although description has been given to anexample of the semiconductor wafer as the object to be processed, thepresent invention is not restricted thereto, and the cleaning methodaccording to the present invention can be readily applied to a glasssubstrate, an LCD substrate, a chemical compound semiconductor substrateand the like.

<Continuous Film Formation of Titanium Film and Titanium Nitride Film>

Description will now be given as to continuous film formation of atitanium film and a titanium nitride film as a related invention of thepresent invention with reference to FIG. 25 and FIGS. 26A to 26D. Thistechnique is a related technique of the technique disclosed in Jpn. Pat.Appln. KOKAI Publication No. 10-106974 proposed by the presentapplicant. FIG. 25 is a view showing a plasma film-forming system, andFIGS. 26A to 26D are process charts showing processes of film formation.Here, description will be given as to a method of continuously forming atitanium film and a titanium nitride film on a substrate surface of anobject to be processed, e.g., a semiconductor wafer.

A method of forming a titanium film will be first described withreference to a flowchart of FIG. 27.

Exhaust is carried out while purging the inside of the processingchamber with an inert gas (step S21).

Then, when the inside of the processing chamber reaches a desired degreeof vacuum, it is maintained (step S22).

A wafer is mounted on the mounting table in the processing chamberthrough a non-illustrated vacuum load lock mechanism while maintainingthe vacuum state (step S23).

Thereafter, the wafer is preheated while introducing a process gas (forexample, an Ar gas and an H₂ gas) into the processing chamber (the waferis preheated to the same temperature as that of the film-formingprocess) (step S24).

Then, the TiCl₄ gas is not introduced from the gas supply system intothe chamber but caused to flow through an evac line provided as a bypassfor a predetermined time. After a quantity of flow is stabilized, anon-illustrated preflow valve is operated, and this gas is introducedinto the processing chamber (step S25).

This causes the TiCl₄ gas to be introduced into the processing chamberafter stabilizing a quantity of flow thereof.

Further, when a quantity of flow of the TiCl₄ gas is stabilized at thestep S25, the preflow valve is switched, the TiCl₄ gas is introducedinto the processing chamber, and plasma discharge is started (step S26).At this moment, a time lag until the gas reaches the inside of theprocessing chamber occurs. However, even if a high-frequency powersupply is turned on simultaneously with switching of the preflow valve,a lag of the plasma discharge also occurs since a response of ahigh-frequency matching device is slow. Therefore, the time lag and thedelay of the matching response are canceled out, and the plasmadischarge is consequently smoothly started. However, if the gas line isshort and there is no time lag in introduction of the TiCl₄ gas into theprocessing chamber, the timing must be adjusted so as to increase aspeed of response of the high-frequency matching device or perform TiCl₄gas introduction adapted for the response of the high-frequency matchingdevice.

With this plasma discharge, a Ti film is formed on the wafer (step S27).Supply of the TiCl₄ gas is stopped, residues (film-forming components)in the chamber are exhausted while being replaced with a plasma gas (Arand H₂ gases), the plasma gas being introduced in the chamber (stepS28).

Then, an NH₃ gas is further introduced into the processing chamber, andthe formed titanium film is subjected to a pre-nitriding process (stepS29). Thereafter, the high-frequency power supply is turned on, theplasma is generated, and the pre-nitrided titanium film is furthernitrided with a nitride gas (Ar, H₂ and NH₃ gases) (step S30). Then, theplasma discharge is stopped, the nitride gas is introduced continuously,and the residues in the processing chamber are exhausted and removed(step S31). Subsequently, the wafer subjected to a film-forming processis carried to the outside from the inside of the processing chamber(step S32).

As to process conditions of the pre-nitriding process at the step S29, aquantity of flow of the H₂ gas is 500 to 4000 sccm, a quantity of flowof the Ar gas is 280 to 2500 sccm, and a quantity of flow of the NH₃ gasis 200 to 3000 sccm. Preferably, a quantity of flow of the H₂ gas is1000 to 3000 sccm, a quantity of flow of the Ar gas is 750 to 2250 sccm,and a quantity of flow of the NH₃ gas is 650 to 2100 sccm. A ratio of aquantity of flow of the NH₃ gas to a total gas flow quantity is 0.026 to0.8 or, preferably, it is 0.16 to 0.36. A ratio of a quantity of flow ofH₂ is 0.07 to 0.9 or, preferably, it is 0.18 to 0.68. In addition, aratio of flow quantity of the NH₃ gas to the H₂ gas is 0.05 to 3 or,preferably, 0.2 to 2. Furthermore, as to process conditions of thenitriding process at the step S30, the plasma is generated with the samequantity of flow as that at the step S29 and the Ti film is subjected toplasma nitriding. As to film-forming conditions of the Ti film at thestep S27, a quantity of flow of TiCl₄ gas is 2 to 20 sccm, a quantity offlow of Ar gas is 500 to 10000 sccm, a quantity of flow of H2 gas is 500to 10000 sccm or, preferably, a quantity of flow of TiCl₄ gas is 4 to 16sccm, a quantity of flow of Ar gas is 800 to 3200 sccm, and a quantityof flow of H₂ gas is 200 to 7500 sccm. A ratio of a quantity of flow ofTiCl₄ gas to a total gas flow quantity is 0.00017 to 0.02 or preferably0.00037 to 0.0057, and a ratio of a quantity of flow of TiCl₄ gas to H₂gas is 0.002 to 0.038 or preferably 0.00053 to 0.008. A titanium (Ti)film with the good quality can be formed by performing the film-formingprocess with the above-described flow quantity ratios.

A film-forming method of a titanium nitride film will now be describedwith reference to a flowchart of FIG. 28.

The inside of the processing chamber is first purged with an inert gaswhile performing exhaust (step S41). Then, introduction of the inert gasis stopped.

When the inside of the processing chamber reaches a desired degree ofvacuum, this state is maintained (step S42). A wafer is mounted on amounting table in the processing chamber through a non-illustratedvacuum load lock mechanism while maintaining the vacuum state (stepS43).

Further, a process gas other than TiCl₄ gas (for example, an N₂ gas andan NH₃ gas) is introduced into the processing chamber, the flow rate ofwhich is gradually increased (step S44). This is carried out because awarpage may be probably generated to the wafer when the process gas isintroduced into the processing chamber so as to rapidly increase aquantity of flow of this gas.

Thereafter, the wafer is preheated while introducing the process gas (N₂and NH₃ gasses) into the processing chamber (wafer is previously heatedto the same temperature as that of the film-forming process before theprocess) (step S45).

Then, after the TiCl₄ gas is not introduced into the chamber buttemporarily caused to flow to an evac line provided as a bypass from thegas supply system for a predetermined time and a quantity of flowthereof is stabilized while introducing the process gas (N₂ and NH₃gasses), a non-illustrated preflow valve is operated and that gas isintroduced into the processing chamber (step S46). This is carried outin order to correctly stabilize a quantity of flow of the TiCl₄ gas,introduce this gas into the processing chamber and form a correct filmthickness. In regard to perfect formation of a thin film, since the filmthickness varies due to fluctuations in a quantity of flow of thematerial gas, this processing is important.

A TiN film is formed on the wafer in this gas atmosphere (step S47).Then, when the TiN film is formed to a desired thickness, supply of theNH₃ and TiCl₄ gasses is stopped, and residues (film-forming components)in the chamber are purged and exhausted while introducing the N₂ gasinto the chamber (step S48).

Then, the NH₃ gas is further introduced while leading the N₂ gas intothe processing chamber, and the TiN film is further nitrided (step S49).This is carried out in order to subject a chlorine component in theformed TiN film to reduction nitriding and removal. Furthermore,introduction of the NH₃ gas is stopped, and residues in the processingchamber are exhausted and removed while maintaining introduction of theN₂ gas into the processing chamber (step S50). Then, the wafer iscarried to the outside from the inside of the processing chamber (stepS51).

Incidentally, as to process conditions of the film-forming process ofthe TiN film at the step S47, a quantity of flow of the TiCl₄ gas is 10to 100 sccm, a quantity of flow of the NH₃ gas is 20 to 2000 sccm, aquantity of flow of the N₂ gas is 500 to 12220 sccm or, preferably, aquantity of flow of the TiCl₄ gas is 25 to 60 sccm, a quantity of flowof the NH₃ gas is 100 to 1000 sccm, and a quantity of flow of the N₂ gasis 500 to 6000 sccm. A gas flow quantity ratio of the TiCl₄ gas to atotal gas flow quantity is 0.000087 to 0.16 or preferably 0.0036 to0.09, and a flow quantity ratio of the TiCl₄ gas to the NH₃ gas is 0.005to 5 or preferably 0.025 to 0.6. Moreover, as to process conditions ofthe nitriding process at the step S49, a gas flow quantity ratio of theNH₃ gas to the total gas flow quantity is 0.0016 to 0.8 or 0.016 to0.66. A TiN film with the good quality can be formed by the film-formingprocess with the above-described ratios.

A concrete example using such a plasma film-forming system as shown inFIG. 25 will now be described.

In this plasma film-forming system, a resistance heater (not shown) isembedded in the mounting table provided in the processing chamber 201.The wafer 203 is heated to a predetermined temperature, e.g.,approximately 400° C. by this resistance heater and, for example, an Argas as a film-forming process gas and a gas including an H₂ gas, an SiHgas and a Ti gas as a reduction gas are introduced from the shower headportion 204 into the processing chamber 201 in predetermined quantities.Also, a high-frequency voltage of 450 kHz to 60 MHz is applied to theshower head portion 204, and the plasma is generated, thereby forming atitanium film. For example, as gasses including titanium, there areTiCl₄, Til₄, TiBr₄, organic Ti, Ti (C₂H₅)₃ gasses.

A process pressure at this moment is 0.5 to 10 Torr or, preferably, 1 to5 Torr. Under this condition, as shown in FIG. 26A, a titanium film 303is selectively deposited on a conductor (substrate) 301 exposed at thebottom of a contact hole 302 opened to the insulating layer 306. In thiscase, TiSi₂ is formed in the self-matching manner from the reaction withSi in the substrate simultaneously with film formation of Ti. Athickness of this titanium film 303 is, e.g., 5 to 50 nm and,preferably, 10 to 30 nm.

In this manner, upon completion of the titanium film-forming process,the substrate 301 is subjected to a titanium nitriding process at thesame mounting position. At first, after stopping supply of the processgas for titanium film formation, the process gas atmosphere in theprocessing chamber 201 is exhausted during supply of Ar and H₂ gasses.Then, as the plasma nitriding gas, a gas obtained by mixing the Ar gas,the H₂ gas and at least one of the N2, NH3 and MMH (mono methylhydrazine) gasses or the respective gasses are individually suppliedfrom the shower head portion 204 into the processing chamber 201 andmixed in the chamber. The nitrided gas atmosphere is formed in theprocessing chamber 201 by introducing the nitriding gas. Then, ahigh-frequency voltage of 450 kHz to 60 MHz is applied from ahigh-frequency power supply 205 to the shower head portion 204 whichbecomes an upper electrode through a matching box 206, and the nitridingplasma is generated in the chamber.

As a result, the surface of the titanium film 303 is subjected to thenitriding process, and a nitrided film 304 is formed as shown in FIG.26B. Moreover, nitriding is possible by supplying the mixed gas of H₂+N₂or N₂+NM₃ or H₂+NH₃. More preferably, the mixed gas consists ofAr+H₂+NH₃. In this case, all of the titanium film may be nitrided.

As nitriding process conditions at this moment, quantities of therespective gases to be supplied are as follows. H₂: approximately 250 to3000 sccm, N₂: approximately 50 to 1000 sccm, NH₃: approximately 50 to1000 sccm, and MMH: approximately 1 to 100 sccm. The process pressure isapproximately 0.5 to 10 Torr or preferably 1 to 5 Torr, and the processtemperature is approximately 350 to 700° C. Moreover, the high-frequencypower is 100 to 2000 W, and preferably 500 to 1000 W. It is to be notedthat appropriately selecting each of quantities of flow of the H₂ gas,the N₂ gas, the NH₃ gas and the MMH gas can suffice and these quantitiesof flow are not restricted to those mentioned above.

This nitriding process improves the adhesion of the Ti film and the TiNfilm. That is, an unreacted product such as TiCl₄ in the Ti film or onthe surface of the Ti film is reduced and Ti is nitrided. In addition,since TiCl₄, which is the film-forming gas, etches the Ti film whenforming the TiN film after formation of the Ti film, this process cansuppress such etching.

Upon completion of the titanium nitriding process in this manner, thesubstrate 301 is moved into another film-forming system which ismaintained in a vacuum state in advance, and there is carried out afilm-forming process in the film-forming system to form such a titaniumnitride film as sown in FIG. 26C by using the known processing method. Atitanium nitride film 305 which functions as a barrier metal layer isformed by CVD on the inner wall surface of the contact hole 302 and theentire upper surface of the insulating layer 306.

As the process gas in this process, for example, TiCl₄, NH₃ and N₂ canbe used. Additionally, the process temperature is approximately 400 to600° C., and the process pressure is approximately 0.1 to 10 Torr orpreferably 0.5 to 5 Torr. Further, a TiN film can be formed byalternately passing the TiCl₄ gas and the NH₃ gas. Based on this, thedensity of chlorine impurities can be reduced, and a film with thehigh-barrier property can be formed.

When this titanium nitride film-forming process is terminated, theprocessed substrate 301 is carried out from the film-forming system, andthereafter a conductive material 307 such as tungsten, aluminium orcopper is embedded in the contact hole as shown in FIG. 26D.

When subjecting the surface of the titanium film to the nitridingprocess in this manner, the plasma is generated in the atmosphere of amixed gas consisting of the Ar gas, the H₂ gas and at least one of theN₂ gas, the NH₃ gas and the MMH (mono methyl hydrazine) gas, and thesurface of the Ti film is nitrided. Therefore, the adhesion with the TiNfilm is improved, and peeling from the substrate can be suppressed. Inthe conventional method using only the N₂ gas or only the NH₃ gas, alarge quantity of nitrogen radicals with a high nitriding capability isgenerated and the TiClx by-product material on the surface of the Tifilm or in the Ti film is not reduced. Therefore, nitriding Ti issuppressed, the adhesion is lowered, and peeling occurs.

However, as a result of performing the plasma process by using the mixedgas consisting of the Ar gas, the H₂ gas and at least one of the N₂ gas,the NH₃ gas and the MMH (mono methyl hydrazine) gas, active hydrogenatoms reduce the TiClx by-product material on the surface of the Ti filmor in the Ti film and remove Cl, and the active Ti and the active Nradical react with each other, thereby efficiently nitriding the surfaceof the Ti film. Accordingly, the adhesion with the TiN film is improved.For verification, the present applicant actually performed the titaniumfilm-forming process and the nitriding process, formed the TiN filmwhich is the barrier metal, and carried out a scratch test. However,peeling of the film from the substrate was not confirmed.

Moreover, when the plasma nitriding process is performed by using themixed gas consisting of the Ar gas, the H₂ gas and at least one of theN₂ gas, the NH₃ gas and the MMH gas in this manner, there can beobtained a result that the contact resistance can be greatly reduced.That is because gasses such as Cl₂ or HCl are removed to the outside ofthe system by removal of Cl by strong reduction of the TiCl₄ materialremaining in the titanium film by the H₂ gas and degasification from theby-product, and hence chlorine (Cl) which can be factor of an increasein resistance does not remain in the film or on the surface of the film.

Since the nitriding process of the titanium film surface is carried outby the plasma process in the atmosphere of the mixed gas consisting ofthe Ar gas, the H₂ gas and at least one of the N₂ gas, the NH₃ gas andthe MMH gas, the contact resistance can be greatly reduced, and a stablenitride can be formed from the by-product in the chamber which isgenerated in formation of the titanium film. Therefore, peeling of thisnitride can prevent the particles from being produced.

Here, description will now be given as to a result obtained byperforming evaluation of a change in degree (%) of the chip numberdepending on presence/absence of each gas or when changing a quantityfollow.

FIGS. 29A to 29D are views showing degrees (%) of the chip numberdepending on presence/absence of each gas or when changing a flowquantity. Here, the degree of the chip number is shown as a resistancevalue, but this is a ratio of the chips in a range of arbitraryresistance values. In addition, FIG. 38A shows the relationship betweenan NH₃ gas ratio relative to the entire gas and the degree of the chipnumber, and FIG. 38B is a view showing the relationship between an NH₃gas ratio relative to the H₂ gas and the degree of the chip number.

FIG. 29A shows the degree of the chip number when the H₂ gas and the N₂gas are used without the NH₃ gas and a quantity of flow of the H₂ gas ischanged. FIG. 29B shows the degree of the chip number when the N₂ gasand the NH₃ gas are used without using the N₂ gas and a quantity of flowof the NH₃ gas is changed, and FIGS. 27C and 29D show the degrees of thechip number when all of the N₂ gas, the H₂ gas and the NH₃ gas are usedand a quantity of flow of the NH₃ gas is changed. Further, a quantity ofthe N₂ gas is 50 sccm in FIG. 27C, and a quantity of the N₂ gas is 500sccm in FIG. 29D. Besides, the Ar gas is used as the plasma gas.

In the example shown in FIG. 29A, the degree of the chip number isincreased as a quantity of flow of the H₂ gas is increased. However, aquantity of the H₂ gas must be increased to approximately 2000 sccm andcaused to flow. Furthermore, in the example shown in FIG. 29B, althoughthe degree of the chip number is increased as a quantity of flow of theNH₃ gas is increased, the extent of increase is low. When a quantity ofthe NH₃ gas is approximately 400 sccm, the degree of the chip number isapproximately 90% and does not reach 100%. On the other hand, in theexample shown in FIG. 29C, a quantity of flow of the N₂ gas is 50 sccm,and the degree of the chip number is increased as a quantity of flow ofthe NH₃ gas is increased. The extent of increase is high, and the degreeof the chip number reaches approximately 100% when a quantity of flow ofthe NH₃ gas is approximately 400 sccm. Furthermore, in the example shownin FIG. 29D, a quantity of flow of the N₂ gas is set to 500 sccm whichis a large number, and the degree of the chip number stably maintainsapproximately 100% when a quantity of flow of the NH₃ gas is not lessthan 50 sccm.

According to the cleaning method of the film-forming system of the thirdembodiment mentioned above, the number of particles actually flowingthrough the exhaust system is measured. The number of particles isreduced after the peak, and a time when the number becomes lower than apredetermined quantity is judged as a just etch timing. Based on thisjudgment, setting of the end pint to terminate the cleaning process canbe appropriately set. Therefore, excessive over-etching in the cleaningprocess can be avoided without being affected by the number ofaccumulated objects subjected to the process before the cleaningprocess. Therefore, not only reduction in duration of the life of thestructure in the chamber can be prevented but also wasteful consumptionof the cleaning gas can be suppressed.

Here, description will now be given as to a structure of a deliverymechanism for an object (for example, a wafer or a glass substrate) onthe mounting table adopted in this embodiment.

Known delivering mechanism, such as shown in FIG. 1, have a structurethat a plurality of push-up pins used to support the wafer respectivelymove up and down through pin insertion holes of the mounting table. Inthis structure, when the push-up pins move up and down and pass throughthe pin insertion holes in order to deliver the wafer, they may slidewhile coming into contact with the inner wall of the pin insertion holesand generate particles if the sliding accuracy is deteriorated orthermal deformation occurs. The generated particles enter the gasatmosphere in the vicinity of the wafer and adhere to the surface of thewafer when forming a film, which leads to a defect in a circuit pattern.Moreover, they adhere on the back side of the wafer, which can be afactor of bringing the particles into another chamber when carrying thewafer. In addition, the end of the push-up pin may collide with theopening portion of the pin insertion hole and the push-up pin may bedamaged in some cases.

In addition, when the wafer is moved up, the mounting position of thewafer on the mounting table may be shifted or the wafer may fall fromthe above of the push-up pin due to vibrations caused by sliding of thepush-up pin or existence of a gas in a space between the back side ofthe wafer and the mounting surface of the mounting table (however, itdepends on the degree of vacuum in the processing chamber).

Thus, in the delivering mechanism adopted in this embodiment, therespective push-up pins are inserted into a plurality of pin insertionholes of the mounting table. This push-up pin is formed to have a lengthwhich can be accommodated in a range of a depth of the pin insertionhole. A push-up member which pushes up the respective push-up pins fromthe lower side (direction along the pin insertion holes) is connected.The push-up pins smoothly move up and down from the upper surface of themounting table (wafer mounting surface) by moving up and down thepush-up member (positioning drive pin) with a predetermined stroke.

Concretely, as shown in FIGS. 30A and 30B, the entire body of thepush-up pin 311 is formed of ceramics or quartz, and the push-up pins311 are respectively fitted into a plurality of pin rod insertion holes312 provided to the mounting table 202. In this case, the outsidediameter of the push-up pin 311 is similarly smaller than the insidediameter of the pin rod insertion hole and a small gap 313 is formedtherebetween. This pin rod insertion hole 312 communicates with a spaceS1 between the back side of the wafer W and the upper surface of themounting table 96 and a space S2 on the back side (lower side) of themounting table 202 through the gap 313.

This push-up pin 311 has a flat upper end surface, and a fitting hole314 is formed to the lower end of this pin so as not to allow insertion.The upper end part of the positioning drive pin 315 is inserted andfixed in this fitting hole 314. The lower end of the positioning drivepin 315 pierces and is fixed to the push-up member 316. This push-upmember 316 is connected to a later-described actuator 317 shown in FIG.25 and driven upward and downward. A stopper 317 to restrict upwardmovement is provided to the lower side of the positioning drive pin 315.A lifting position of a catch-up pin may be defined by bringing it intocontact with the stopper and stopping it when lifting up.

With such a structure, as shown in FIG. 30A, the positioning drive pin315 and the push-up pin 311 move up by lifting drive of the push-upmember 316, and the wafer W is delivered to a non-illustrated carryingarm. On the contrary, as shown in FIG. 30B, the positioning drive pin315 and the upper surface of the push-up pin 311 move down so as to beparallel with or lower than the upper surface of the pin rod insertionhole 312 of the mounting table 202 by downward drive of the push-upmember 316, and the supported wafer W is mounted on the upper surface ofthe mounting table 202. The wafer W is held by a non-illustratedelectrostatic chuck mechanism provided to the mounting table 202.

Now, FIG. 25 shows a structural example of the processing system havingmounted therein the push-up pin having such a structure and their drivemechanism.

The processing chamber 201 is connected to a non-illustrated load lockchamber through a gate valve, and can maintain the vacuum state byexhausting the inside of the both chambers. The wafer is carried betweenthese chambers by a non-illustrated carrying arm. Further, anon-illustrated resistance heater is embedded in the mounting table 202having the wafer W mounted thereon, and the wafer can be heated to adesired temperature and stably maintained.

The insides of the load lock chamber and the processing chamber 201 arefirst maintained at the high degree of vacuum. The wafer W to beprocessed is held by the carrying arm and carried to a predeterminedposition in the processing chamber 201 through the opened gate valve anda carry-in entrance. At this moment, when the actuator 317 is driven andthe push-up member 316 is moved up as shown in FIG. 30A, the positioningdrive pin 315 moves up to a delivering position (uppermost position)from a standby position (lowermost position). The upward movement of thepositioning drive pin 315 pushes up the push-up pin 311 so as to bepushed up from the pin insertion hole 312. The upper end of the push-uppin 311 pushes up the wafer W held by the carrying arm, and the wafer Wis consequently delivered from the carrying arm to the push-up pin 311.Thereafter, the carrying arm is retired.

Then, when the actuator 316 is driven and the push-up member 316 ismoved down as shown in FIG. 30B, the positioning drive pin 315 and thepush-up pin 311 move down, and the push-up pin 311 is completelyimmersed in the pin insertion hole 312. At this moment, the wafer W isalso moved down and mounted on the upper surface (mounting surface) ofthe mounting table 202 and held by a non-illustrated electrostatic chuckmechanism. Thereafter, various processes, such as film-forming processesof Ti and TiN films or a nitriding process are applied to the wafer W.

Furthermore, upon completion of the processes, the push-up member 316 isagain moved up. The positioning drive pin 315 is pushed up by thisupward movement, and the push-up pin 311 having the wafer W mountedthereon is moved up. The carrying arm is inserted under the lifted waferW, and the wafer W is delivered to the carrying arm by downward movementof the push-up pin 311. The wafer W is carried to the outsidesimultaneously with evacuation of the carrying arm.

With this structure, since the push-up pin 311 inserted into the pininsertion hole 312 smoothly moves up and down with a small contact whendelivering, it is possible to avoid the contact which generatesparticles or collision or sliding which may damage the push-up pin.

Moreover, since the space S1 between the back side of the wafer W andthe mounting surface of the mounting table 202 communicates with thespace S2 on the back side (lower side) of the mounting table 202 throughthe gap 313, it is possible to let the gas existing in the space S1 outto the space S2 when moving down the wafer or prevent shifting of themounting position or falling of the wafer which occurs when the space S1is formed in the state that the back side of the wafer W is appressedagainst the mounting surface in the case of moving up the wafer W.

FIG. 31 shows a cross-sectional structure of a first modification of thedelivering mechanism. Although the push-up pin 311 is supported by theupper end part of the positioning drive pin 315 in the deliveringmechanism mentioned above, a flange portion 315 c is provided in themiddle of the positioning drive pin 315 and the push-up pin 311 issupported by the flange portion 315 c of the positioning drive pin 315in this modification. Other structures are equivalent to that of thedelivering mechanism mentioned above.

This positioning drive pin 315 has the outside diameter of the upperpart 315 a which is fitted to the fitting hole 318 of the push-up pin311 being slightly smaller than the inside diameter of the fitting hole318, and has a gap between itself and the push-up pin 311. Moreover, theoutside diameter of the flange portion 315 c of the positioning drivepin 315 is slightly smaller than the inside diameter of the pininsertion hole 312, and there is a gap 313 between the flange portion315 c and the inner wall of the pin insertion hole 312. In addition, theoutside diameter of the lower part 315 b of the positioning drive pin315 is smaller than the inside diameter of the pin insertion hole 312,and there is a gap between the lower part 315 b and the inner wall ofthe pin insertion hole 312.

With this structure, in addition to the effects and advantages of thedelivering mechanism mentioned above, since the push-up pin 311 issubstantially vertically held in the fitting hole 318, the push-up pin311 can be prevented from being inclined when moving, and the push-uppin 311 can be smoothly moved up and down with less contact.

Additionally, a reference position (lowering position) and a deliveringposition (lifting position) of the push-up pin 311 can be readilyadjusted by adjusting fixing positions of the positioning drive pin 315and the push-up member 316.

In this modification, the lower end part 315 d of the positioning drivepin 315 is fixed to the push-up member 316 by a nut 320 and the like.However, when there is no high requirement in the positioning accuracy,the lower end part 315 d and the push-up member 316 may be slidablyattached in a given range. With such a structure, even if the push-upmember 316 expands and contracts due to heat, the influence of theupward and downward fluctuations of the push-up pin 311 can be reduced.It is to be noted that the gap 313 is likewise provided between thepush-up pin 311 and the pin insertion hole 312 in the secondmodification and hence the gas passes through the gap 313 during theupward movement and shifting of the position of the wafer W on themounting surface or falling from the push-up pin 311 and the like can beprevented.

FIG. 32 shows a cross-sectional structure of a second modification ofthe delivering mechanism mentioned above. In this second modification, agap 319 is provided between the wall surface of the fitting hole 318 andthe upper part side surface of the positioning drive pin which is fittedin this fitting hole 318, and there is provided a free stated that onlythe upper end part is in contact. It is to be noted that a plurality ofthe push-up pins 311 are provided to the mounting table 202. Clearancesin the gaps 313 between these push-up pins 311 and the respective pininsertion holes 312 are equivalent to each other, and these push-up pins311 move down all at once at the same speed even in the free state.Further, the lower end part of the positioning drive pin 315 is fixed tothe push-up member 316 by a nut 320 and the like.

With such a structure, the effects and advantages similar to those ofthe above-described delivering mechanism can be obtained, and since thegap 319 is provided between the push-up pin 311 and the positioningdrive pin 315, heat generated in the mounting table 202 is hardlytransferred to the positioning drive pin 315, thereby preventing thermaldeformation and the like of the positioning drive pin 315.

FIG. 33 shows a cross-sectional structure of a third modification of theabove-described delivering mechanism.

In this third modification, a plurality of push-up pins 311 with a shortlength are formed so as not to pierce the pin insertion holes 312 formedto the mounting table 202. There is provided a structure to assuredlymove down the push-up pins 311 by a stopper-like function when movingdown these push-up pins 311.

As shown in FIG. 33, an evagination portion 321 which protrudes in theform of a flange is formed at the upper end part of the positioningdrive pin 315. Furthermore, a constriction portion 322 is formed at alowermost part of the fitting hole 318 of the push-up pin 311. Themaximum outside diameter dimension of the evagination portion 321 isformed so as to be larger than the minimum inside diameter dimension ofthe constriction portion 322, namely, it is good enough that theevagination portion 321 is caught by the constriction portion 322 anddoes protrude from the fitting hole 318. The evagination portion 321 andthe constriction portion 322 are a male screw and a female screw,respectively, and the upper end part of the positioning drive pin 315 isinserted into the fitting hole 318 by screwing the evagination portion321. It is to be noted that the evagination portion 321 and theconstriction portion 322 may be engaged by not only the screw shapes butalso by forming, e.g., a key way to the constriction portion 322,forming a key protrusion portion (fitting to the key way) which partlyprotrudes to the evagination portion 321, fitting and rotating this keyprotrusion portion. However, the key way must have a double-laminationstructure or a stopper must be provided inside of the key way in orderto prevent the key protrusion portion from easily bursting through.Moreover, the lower end part of the positioning drive pin 315 is fixedto the push-up member 316 by a nut 320 and the like.

With such a structure, when moving down the positioning drive pin 315and returning the push-up pin 311 into the mounting table 202, providingthe constriction portion (or the key way) 322 to the push-up pin 311enables engagement with the evagination portion (or the key protrusionportion) 321 and forcible downward movement. Further, since the gap 319is provided between the push-up pin 311 and the positioning drive pin315, heat generated on the mounting table is hardly transferred to thepositioning drive pin 315, thereby avoiding thermal deformation and thelike of the positioning drive pin 315. Furthermore, play of the upperend part of the positioning drive pin 315 relative to the fitting hole318 is eliminated by providing the constriction portion 322 at aposition above the bottom of the fitting hole 52 by a length of theevagination portion 321, and the push-up pins 311 can be uniformly moveddown.

FIG. 34 shows a cross-sectional structure of a fourth modification ofthe delivering mechanism mentioned above. This modification is astructure obtained by adding a stopper function of the push-up pins 311to the structure of FIG. 32. That is, a flange portion 323 is providedat an opening part of the pin rod insertion hole 312 of the mountingtable 202 and caused to function as a stopper when the push-up pin 311is moved down (accommodated in the pin rod insertion hole 312). Thelower end part of the push-up pin 311 comes into contact with the flangeportion 323. At this moment, the upper surface of the upper end part ofthe push-up pin 311 is configured to be on the same level as themounting surface of the mounting table 202 or stopped at a positionlower than the mounting surface.

With such a structure, since the push-up pin 311 can be engaged with andsupported by the flange portion 323 when accommodated in the mountingtable 202, the push-up pin 311 can be always stopped at an appropriateposition. Further, since the gap 319 is provided between the push-up pin311 and the positioning drive pin 315, heat generated on the mountingtable 202 is hardly transferred to the positioning drive pin 315,thereby avoiding thermal deformation and the like of the positioningdrive pin 315.

FIG. 35 shows a cross-sectional structure of a fifth modification of thedelivering mechanism mentioned above. This modification has aconfiguration that the structures of the evagination portion and theconstriction portion in FIG. 33 are combined with the structure of theflange portion in FIG. 34 and the positioning drive pin 315 is separatedfrom the push-up member 316. A pin support plate 324 is provided at aposition of the push-up member 316 where it comes into contact with thelower end part of the positioning drive pin 315.

In this structure, when the push-up member 316 is moved up by anon-illustrated actuator and the like, it comes into contact with thelower end part of the positioning drive pin 315 and pushes up thepositioning drive pin 315. Then, the upper end part of the positioningdrive pin 315 moves up, the push-up member 316 comes into contact withthe uppermost part (bottom) of the fitting hole 318, and the push-up pin311 moves up so as to be thrusted out from the pin insertion hole 312.Then, when upward movement of the push-up member 316 is stopped, thepush-up pin 311 is thereby stopped at the wafer delivery position.

Furthermore, when the push-up member 316 moves down, the positioningdrive pin 315 and the push-up pin 311 integrally move down by theirweights. Moreover, the push-up pin 11 comes into contact and engageswith the flange portion, the positioning drive pin 315 moves down, andthe evagination portion of the positioning drive pin 315 comes intocontact and engages with the constriction portion. With the structure ofthe fifth embodiment, it is possible to obtain the effects andadvantages including both the third and fourth modifications.

In the above-described delivering mechanism for an object to beprocessed, the push-up pin pierces the mounting table and does not moveup and down, and the push-up pin having the length equal to or smallerthan the thickness of the mounting table is inserted into the pin rodinsertion hole of the mounting table. The push-up pin is supported so asto be cable of moving in the direction along the pin rod insertion hole,namely, the vertical direction, and the push-up pin smoothly moves upand down by the positioning drive pin. Therefore, generation ofparticles is suppressed, and damage to the push-up pin due to collisionof the end of the push-up pin with the opening part of the pin insertionhole can be avoided. The space between the back side of the wafer andthe mounting surface of the mounting table communicates with the spaceon the back side of the mounting table by the gap provided between thepin rod insertion hole and the push-up pin, and the gas can be smoothlymoved when mounting and removing the wafer onto/from the mounting table,thereby preventing the displacement of the wafer or falling of thewafer. Furthermore, it is possible to avoid shifting of mounting of thewafer or falling of the wafer from the pin due to vibrations caused bysliding of the mounting table and the push-up pin.

1. A processing apparatus comprising: a processing chamber, which isconfigured to be evacuated; a mount table, on which an object to besubjected to a predetermined process is mounted; a gas supply system forsupplying a necessary gas to the processing chamber; an exhaust system,which includes a vacuum pump in a middle portion and evacuates anatmosphere in the processing chamber; a particle measuring device,provided in the exhaust system, for measuring the number of particlesincluded in exhaust gas; and a control section which determines an endpoint of a cleaning process based on a measurement value of the particlemeasuring device, when cleaning gas is caused to flow through theprocessing chamber to carry out the cleaning process.
 2. The processingapparatus according to claim 1, wherein the control section comprises: aparticle number determining portion which determines whether themeasurement value of the particle measuring device is equal to orsmaller than a predetermined particle threshold value; a low particlenumber duration measuring portion that measures a duration, in which thenumber of particles is equal to or smaller than the predeterminedparticle threshold value, based on an output of the particle numberdetermining portion; a just etch timing determining portion, whichdetermines just etch timing based on duration output from the lowparticle number duration measuring portion; an over-etching perioddetermination portion, which determines an over-etching period based ona cleaning process period from start of etching to the just etch timing;and process based on the over-etching period.
 3. The processingapparatus according to claim 2, wherein the just etch timing is a pointin time when most part of unnecessary film on a surface of the mounttable is removed.
 4. The processing apparatus according to claim 1,wherein the exhaust system includes a plurality of exhaust pipes, andthe particle measuring device is provided in at least one of the exhaustpipes.
 5. The processing apparatus according to claim 1, wherein thepredetermined process is a film forming process to deposit thin film ona surface of the object.
 6. A method for cleaning a processing apparatuscomprising: a processing chamber, which is configured to be evacuated; amount table, on which an object to be subjected to a predeterminedprocess is mounted; a gas supply system for supplying a necessary gas tothe processing chamber; a particle measuring device, provided in theexhaust system, for measuring the number of particles included inexhaust gas; and an exhaust system evacuating an atmosphere in theprocessing chamber, the method comprising continuously measuring withthe particle measuring device the number of particles in exhaust gasflowing through the exhaust system, when cleaning gas flows in theprocessing chamber; and determining an end point of a cleaning processbased on a measurement value of the number of particles.
 7. The methodfor cleaning a processing apparatus according to claim 6, wherein thedetermining an end point of the cleaning process includes; measuring aduration, in which the number of particles is equal to or smaller thanthe predetermined particle threshold value; determining just etch timingbased on the duration; determining an over-etching period based on acleaning process period from start of etching to the just etch timing;and determining an end point of the cleaning process based on theover-etching period.